Re: Loose mower belt (L118)
There is a stop for the tensioner arm on the deck that needs to be bent towards the left so that when at rest the tensioner arm doesn't allow as much slack in the belt.
It also appears that the belt retaining guide in the pic may be bent or it may be twisted at it's mounting point. On my current L110 refurb I had to drill out the threads in the plate where that guide bolts on and then use a longer bolt with a nylock nut on top of the plate. There is a stamped 'tab' in the guide that goes in another hole in the plate and often the guide is twisted and this tab isn't in it's alignment hole.
Basically, all the guides for the mower belt are there to keep the belt in the various sheaves even when there is a good bit of slack in the belt. If any one of these guides is missing or bent out of position then the belt is likely to fall out of a sheave somewhere. I often see people trying to use the mower without the plastic cover on the LH spindle. This cover is part of the belt retaining system. On my L110 the cover was broken in the area where a steel guide pin is inserted. I drilled a carefully located hole in the deck shell and added a long 8mm bolt with 2 nuts and washers to take the place of the factory pin. I was then able to use the still functional plastic cover over the spindle.
None of these guides should touch the belt when the PTO is engaged. It's only when you disengage the PTO that the belt moves out and touches the guides.