Hi jefffrombrisbane,
I can relate to the shed clutter. I suspect the drive gear on mine went years ago. I never bothered pulling the drums off to check. It actually works in my favour a bit because I have to pull/push the mower backwards and forwards quite a bit when I reposition the mower in between moss rock nooks along a lengthy retainer wall. That's also where the rear catcher comes into it's own. I don't have any slope to contend with so pushing it along doesn't phase me at all. When it finally dies or becomes too expensive to fix, I'll probably end up buying a Honda push mower as a replacement but being the Sherman Tank that the 590 has been, with a bit of continued TLC, it might just outlast me. I still have my dad's old 430 as a backup.
Diplomatic