I have a Yardman model 675 tractor, 15.5 hp, 42" deck made in 2002. I have rebuilt the mower deck and re-installed it. Then I used the tractor to cut my yard and everything looked great. Now the mower deck will not come up on only one side (left side). I checked the attachment points and they look in place and secure. Does anyone have a clue what the problem is?????