I know Betty Crocker says to cook the bird UNcovered, but I never have. I have a huge roasting pan with a cover that I use. It never takes as long for it to get done as stated in the tables. I think it also stays moister.
In addition to checking the oven temp, which is a great idea as it really sounds as if your oven if off, don't be afraid to check to see how the turkey is doing starting halfway through the time you think it will take. You should be able to judge how much more time it needs to cook.
Another idea is to get yourself a meat thermometer if the bird doesn't have its own timer.
I've never made one using the methods/recipes described. This is the recipe I use. I no longer stuff the bird.
Kosher salt
½ - ¾ tsp lemon pepper
1 tsp thyme
1 tsp ground celery seed
½ tsp lemon zest (I use dried)
¾ tsp orange rind (I use dried)
2 3 oranges or lemons
½ c orange juice or
¼ c lemon juice
Cut 1 orange (or lemon) in half & squeeze juice over outside of bird. Set the squished pieces aside to toss into the cavity after rubbing with spices.
Rub inside & out with Kosher salt.
Combine spices & rub this mixture inside & out.
Toss squished halves into cavity.
Slice 2 oranges (~¼ slices) & slip under the skin on breast & legs.
Squeeze any remaining orange slices into the cavity (to remove juice) & then toss the squished slices in there - including the end pieces.
Add juice to the cavity. (For lemon, I use the frozen Minute Maid lemon juice.)
Cover roaster & roast at at 425 degrees for 20 minutes. Reduce heat to 325 & roasted a couple hours until it is falling off the bones.
If you end up with leftovers you can do this:
I leave the roaster on top of the stove (turned off) while I pull the meat off of what was left of the carcass. It starts to fall apart when you remove the meat. I put the meat in a container & refrigerate it. Then I pour a couple quarts of water in the roaster, positioned it over 2 burners & turned it on medium low for a couple hours. I left the skin & oranges in with the bones. The longer it cooks the better - I like to do it at least 4 hours if I have time.
The meat can be shredded as soon as it's cool enough - or the next day. Once the broth is "done" I wait until it's cool enough to touch the bones when I pull them out. I end up straining the broth to get out all of the disintegrating bones - but there's usually still some meat in there that I pull out & keep. I'm too cheap to just toss it with the bones, skin & stuff.
I usually store the meat IN the broth and I skim off the fat once it had cooled & separated.
Serve the shredded turkey on hard rolls with horseradish sauce & the broth. Yum!
Blech, but 
