Frigidaire Oven problem

Hello and thank you in advance for any help. We have a Frigidaire range model # FGFS68CJBA. About 6 months ago we noticed it would not heat to preheat temps, and then it stopped working one day. We tried again a few days later and all seemed fine. Then again a few nights ago when it was turned on there was no heat at all, and the kitchen filled up with the smell of gas. The range top is still working perfect.

I stopped into Sears and after trying to sell me a new stove over and over he finally said it sounded like a bad glow light? I asked if I could change that, and he tried to tell me it was dangerous. I said ok then tell me is it considered a user serviceable part, to which he replied yes.

So to those that know much more then I do what do you think? The online chat said it was most likely either part AP3220504 or part AP2150412. What do you think? Is it pretty easy to change and which part? We have a party this Friday so I have to do this, or get a new oven in the next day or so, so any help is really appreciated.

Thanks
Kevin

Anyone…any ideas