Well, for starters
try
lack of lubrication.
***
+1
If your lever had that much play in it, you should replace the lever as well, not just the bushing. The excess play in the pivot hole (the one that the bolt goes through) will cause the switch to not work as it should, the result being that if the bike is in gear, you won't be able to start it even though the clutch lever is pulled in.
Lube everything with your favourite goopy grease.