RV Repair: terralab rv furnace, little buggers, counter tops

Question
I just viewed another person's question about their rv furnace not lighting and the expert gave some preliminary suggestions for this person to check out but no actual troubleshooting or repair info. I have a small terralab fau under the stove/oven in my trailer. it has worked fine for the last 5 yrs. However, this year when I set the thermostat the fan comes on to clear the firebox then I can hear the igniter clicking but the furnace never lights. I know there is gas to the unit since the stove works just fine. There does not seem to be much of an access to the unit; just a small air intake door at the unit. no access from unsernieth or outside. Does the stove/oven need to be pulled? But even so, then what? Can anyone out there help me? I am retired, handicapped and live on SS, and cannot afford to have a serviceman come and try and sell me a whole ne unit. Especially when I know the unit is not very old. Personally, I believe the burner may be clogged with spider webs. We got no shortage of the little buggers 'round here. PLEASE help if you can.
Sincerely,
GRM

Answer
pull the unit out to fix it.  only a couple of screws hold it in, but the gas line may be difficult to access.  These are installed before the counter tops.  might be better to cut and splice the propane line.  

my guess is the gas valve is bad or propane cannot flow due to pluggage