I have a Troybilt Bronco 42 inch mower. We sent it to a mower repair shop recently and they said deck engagement needed repair. They said everything was fixed. We brought it home and mowed front yard without problems. The next day we went to mow back yard and the blades would only spin when raised up to highest setting. Also making grinding sound and seems to be knocking over grass more so than cutting it. I'm afraid if I send it back to repair shop will say it isn't their fault and want more $$$. Did the repair shop do faulty work?