My Trane XE78 is going out. I need to identify what part if any I need to replace to get the furnace working.

One morning I woke up to a cold house, it was below freezing outside and a little over 40 degrees in the house. I checked the furnace and found that it didn't have any flame, but was still blowing cold air into the house. I was able to get it to light by cleaning it out with the shop vac and changing the filters. It worked for almost a month then stopped.

I found if I use the hair dryer inside the furnace, it would light. The furnace would work for a few days, then I would have to get the hair dryer out again. I did this for about a month. But today I was not able to get it to light even after using the hair dryer.

I tried to clean it up again using the shop vac and blew out any dust, it still didn't work.

This is what it does.
I press the safety switch
I hear a few clicks and the intake blower starts
The control board light begins to flash asking for heat
The glow plug turns bright yellow
The furnace waits till the glow plug is at its peak
You hear another click and expect the gas to ignite, nothing
The blower keeps going, and the light keeps blinking like it did earlier, but no flame

I turned the power off at the fuse box, waited about 10 secs. and turned it back on, it still didn't light. Any suggestions on what I should try to get this working again?