You are probably wondering how to remove the impeller - generally, these are screwed on to tha motor shaft - motors normally run clockwise when viewed from the rear, so thread is normal right hand. remove fan cowl and fan from motor in order to be able to restrain the shaft while you unscrew the impeller - it should be straightforward from there.

Bearing failure is more often than not brought on by leakaege from the mechanical seal - when you reassemble the pump you should replace the seal assembl - also make sure that there is no damage in the form of melted plastic around the seal stationary seat area; replace parts as necessary.