Briggs & Stratton 675 Petrol Lawn Mower Drive Issue: Wheels Not Turning, Belt Tightened

Hello, I have a Briggs & Stratton 675 petrol lawn mower. The problem concerns the mower drive. When I turn on the drive, the wheels do not turn. After lifting the mower up, the drive works - the wheels turn. The belt is tightened with a screw. When I pull it to the end, the wheels do not turn at all, even when I lift it up. Please help. The mower is only 3 years old and it cost me PLN 1700.

Depending on the design of the gearbox, there may be various damages. There may be worn taper rings (brass) entering the worm wheel gear, or worn teeth (rounded) inside the worm gear wheel in the version with a claw clutch (pin across the shaft driven by the teeth inside the gear wheel).

If you have the latter version, you can deepen the cuspid teeth (plastic) with a manual mini straight grinder. I did it and so far it works.

I see. Before you dismantle the gears, check if you have teeth inside the road wheels, because they may have worn down and the gears do not pull.

And it is possible that some shields in the gear are worn

I dismantled the gears and inside there is a mechanism for the so-called pin and press the shields. In front of the plate I put a brass washer to better press the discs. After folding, something is wrong because the drive works, but I cannot reverse the mower because the wheels are not spinning. I disassembled the gears again and everything is assembled ok. When I removed the upper cap, the wheels spin front and back as it should be. After putting the case back on, it is as before. I don't know what to do anymore.

You cannot reverse because the drive does not disengage (it pulls all the time), or do you turn off the drive (the wheels are standing) and still you cannot reverse the mower?

Probably this washer locks the drive in the engaged position