3 year old MTD 608 Garden tractor

[GFRfan]

3 year old MTD 608 Garden tractor. I use this for mowing and take the 46" deck off for use with a 42" snow blade. The tractor has a column mounted lever for actuation of the pto for the belt driven mower deck. This year, I'm having trouble with the pto lever. Won't stay in the off position while pushing snow and consequently have to hold the lever in the lower position to go in reverse. Part of the mower safety that it won't reverse while the blades are activated. I've checked the manual exploded view and can't find that any springs are missing. Is there anything else I should check on this unit?