Hi John, and welcome to Outdoorking. I've had a look in the owner manual, and it does not tell us whether the gearbox can be dismantled. I've also looked on the internet for spare parts, and only found commonly used spares such as filters, piston rings, clutch parts, etc. I suspect that you have no chance of getting brand new replacement internal parts for the gearbox, and you probably wouldn't want to pay for them anyway for such an old machine. You may find a new gearbox in somebody's "old stock", and you can probably get a second hand gearbox from a mower repairer/wrecker, who may also be able to advise on whether some other gearbox, or entire shaft-and-gearbox, will fit. (An Outdoorking member may also know the answer to that one.) That is about all I can suggest unfortunately.
