Depends on how much you have used it and what kinds of trouble you are having.
It could be simple things related to age, or either simple or more complex problems related to wear and tear.
I have an 85,000 btu that is about 1980 vintage and it works fine. Biggest problem is the grommet where the fuel pickup tube passes thru the top of the tank is bad, and if you fill it real full and move it, some fuel weeps out onto the top of the tank. Beyond that it works like a champ.
Charles
Charles