I have owned two Pro-form treadmills. When this one konks out, I will try a different brand. I didn't know at the time I bought these treadmills and didn't find out until the last one had problems, that Pro-form was considered a low end brand (or at least the models I bought were).
The first piece of advice I will tell you is, like someone else mentioned, get one with a WIDE enough belt. I made sure my belts were the wider ones. Also, I would spend much more than $500. Seriously, I think you will have treadmill problems sooner than later for that low price. Also, I usually never buy the maintenance plan for any purchase, but next time I buy a treadmill, I will seriously consider it.
I love treadmills. I can't live without one. I watch TV and DVDs while on the treadmill. It's my safe haven down in the basement.
I purchased my first pro-form around 1998 for about $550.00. When I tried to put it together, there was a manufacturing flaw that prevented me from hooking the wiring from the upper panel to the part it was supposed to be connected to after it was threaded through the hollow metal side, because they didn't make the cord long enough!
After scraping my hands over this for over an hour, I called the place of purchase (Sportmart). They sent two repair guys out with another treadmill. They had the same problem I did with the new one. The cord was not long enough once you string it through the metal sides. They were here for two hours. They said they usually have these things up and running in 20 minutes, not 2 hours, and that they had never run into this problem before (lucky me). Somehow we got it to work, I can't remember how.
After about seven years of moderate use, my treadmill started acting up. At first it just made some grinding noises underneath and after that I actually can't remember what lead to it's demise, but it felt like it would fall apart while I was on it. When it didn't feel safe to use anymore, I junked it.
Since I felt my first Pro-form served me well, I bought another Pro-form in 2007. The Pro-form Cross Trainer 650. I paid about $600-700 for it, if memory serves. The guy at Sports Authority put it in the back of my van and I, my husband, and grown son, lugged it out of the van and into the basement. The following day, my other son came over to help me put it together. When I get my next treadmill, I will pay extra to have it delivered and put together because it was a LOT of work lugging it down the stairs, etc. It was also no cake walk putting it together.
I thought this treadmill would last about seven years like the first one, but after about three and a half years, the walking belt started slipping to the point that I had to hold on for dear life with both hands while using it and had a few close calls. Eventually, it was no longer safe to use at all. I was so bummed!
I will also say that after only a year of moderate use, the beepers on the panel stopped working. That was my first indication that this Pro-form might not make it as long as the last one, but it wasn't too big a deal since everything else still worked (until the walking belt slipping started up anyway).
Feeling really sad that I no longer had a working treadmill and not sure if it was worth having a repair person come out and not wanting to spend the money for a new one, I did something totally out of character. I tried to figure out what the problem was and wondered if, even though I am not technically inclined, could I fix this treadmill myself?
First I ordered some of that treadmill spray that goes under the walking belt. Of course that would have been too easy of a fix, so naturally it didn't work.

My treadmill was the type that didn't require any spray anyway, but at that point, I was desperate to try anything.
The user manual doesn't tell you much at all because they don't want to be liable for any injuries you may incur while attempting to fix your treadmill (with good reason, I might add).
So began my quest for trying to figure out how to fix my treadmill... trying to narrow down the problem by process of elimination. After countless hours viewing outdated you tube videos on treadmill repair and countless photo tutorials that were so old that the photos were no longer online, it appeared that I might need to replace the motor drive belt. *sigh* For someone like me, this seemed like an insurmountable task and I didn't even know if it would work. It meant removing the plastic housing that covers the motor and tinkering with the unknown. I felt that once I took things apart, I'd never get them back together again. I know this is long, bear with me, I'm hoping it might help someone else in some way.
I ordered the motor drive belt I needed on
amazon (or was it ebay or even the treadmill doctor, can't remember). It was only about $10-20, if memory serves. After about four hours of crying and swearing, I finally got the old belt off and the new motor drive belt on. At one point I had the whole walking belt undone. I never thought I could get it back together and I never thought this would work because I didn't even know if this was indeed the problem, it just seemed like the most likely one.
There were times during this four hours that I thought I would smash my fingers in the pulley mechanism and I thought maybe I was being really stupid trying to do this myself because of that, but I had come this far and just prayed that it would work. Something kept making me press on. I did everything myself until it came time to do the final tightening/tension adjustment. For that I needed my dear but equally unhandy husband to just kneel on one part while I tightened the other part.
The moment of truth came when I turned on the treadmill and much to my shock and amazement, it worked and it was SMOOTH with no skipping at all. I think I cried. I really do love have a working treadmill and I can't tell you how proud I was of myself for fixing my own treadmill. Seriously, this was one of my proudest moments, lol.
That was January 2012. Here we are a year later and it's still working. I don't know how long this will last, but I can't live without a treadmill. Would I ever try to fix another one again? Probably not. So the next time I buy one, I will spend more money and it will not be a Pro-form.
I hope this wasn't too far off topic. I know it was much more than you asked for, but like I said, I'm hoping my treadmill tale of woe might help somebody down the line. I'd be interested to hear what brands are worth looking into.
Good luck!!!