Recently I've noticed that when I mow up hill with a load on it, it bucks a bit along with a clanking noise. Do you think I've broken a tooth or two off a gear or could it be the clutch ? I don't notice anything when I'm level or turning.
I think it could feel like that, but if it were actually jumping in and out of gear, it would destroy the tranny in short order. Your description of it acting normal while on the level and turning makes me think no gears are damaged at this point. I suppose it is also possible that the key has sheared on the transaxle drive pulley.
Take a good look at the (4) rubber engine mounts, especially where the metal part is molded into the rubber. Are they broken or have missing rivets? Use a pry bar to try to lift or rock the engine toward the rear. Check the engine cradle at the welds. Check the drive belts too.
We might be wrong but these things are the usual suspects. Let us know what you find!
Well, it was time to mow again. The motor mounts are fine and there's no sign of a crack anywhere on the frame. It's a nice rust-free solid unit. It still had the bucking and clunking noise when going uphill in each forward gear.