I had my Troybilt lawnmower repaired last year to get the front wheel drive?

I had my Troybilt lawnmower repaired last year to get the front wheel drive to work. The mower was working when I stored it for the winter - now the mower cuts grass, but once more, I have to push it because the front wheel drive does not work. The "fix" last year cost what the mower cost. Is there some way I can tell if this is an intermittent problem that I can solve?