My furnace just went on the fritz about 4 days ago after starting to run very loudly. I open the unit and started playing with few switches and maually turn this big round looking knob, for lack of a better word. Oddly enough the unit kick into gear and work for about two days. Now the furnace will only work if I apply some slight pressure to the center screw which hold that knob. If I apply too much pressure the wheel won't turn and if I release the pressure prior to pilot lite and heat coming on the unit won't turn on. Once unit hits the desired temp requested the unit come to a very loud grinding hult.

Anyone out there expereince this situtation with their Goodman GMT unit? By the way the unit is only 3 years old.

You are way in over your head on this one. It will take a professional to come to your site for the repair. The grinding is usually the blower motor but the rest of the items you have placed way out of adjustment by now. It is always a shame that people start twisting and turning things around when they have no idea of what they are doing. Naturally the worst part of this is that it will cost big $$$$ to fix it now. Good luck with your repair.