Front mount rotary mower belt slippage.

[pfrederi 18,700]

Been using (abusing) the 42" side discharge on the front mount.  In really heavy grass/brush you can hear the blades slow down.  I do not think the PTO clutch is slipping as it takes some effort to engage it.  I can't tell if it is eh PTO to deck belt or the deck belt itself that is slipping.  Any ideas how to "tighten" them up???

 

I do use this poor thing almost as a bush hog in places the big tractor and hog can't go....

[squonk 43,874]

First thing I would do Paul is take the covers off the deck and clean all the grass and boogers that are around the belt and slider. Make sure the slide is free. Then the belt. It may be worn to the point where it is bottoming out on the pullies. Same with the PTO belt . I  have seen belts that look fine but have narrowed so much they don't grip the sides of the pullies.