I wasn't aware the mower was belt driven other than the blades. It is a 5-speed with clutch...Granted I'm sure the belt has not been replaced in many years but it appears to be pretty good with minimal dry rot, etc.Welcome Gary!
If the engine is running smooth, first place I would look is to see if the belt might be slipping.
It not only lugs when I mow with it but when the blades are not engaged as well...it feels as though something is slipping and then lunges forward until it propels forward for maybe another 10 feet or so then slips again. It also feels like the rear axle may have lost a couple splines causing it to disengagement with a gear/s...does this make sense??? lol
Gary
