I've been around a few ZD series machines in my time and the spindle bearing job is one you can handle if you've got patience and a clean workspace. First thing I'd ask is whether you've got the workshop manual for the ZD21. It lays out the disassembly steps and torque specs, which come in handy when you're dealing with the spindle housing and pulley stack. You'll need to remove the deck, pull the spindle assembly and press out the old bearing using a proper tool setup. Make sure to inspect the shaft and housing for wear while you're in there and replace the seals too if they show any signs of damage.My 2005 ZD21's left blade spindle bearing failed, and I plan to replace it myself. Is anyone familiar with this process?
Thanks!