Always make sure the equipment is unplugged from the electricity before doing any work on it.

hi I don't know why your trimmer squeeks but it could be that it needs grease in the cam housing. if you have to ask this question perhaps you should ask a friend who has experience of maintaining this equipment to give a little advice, assistance.. https://www.youtube.com/watch?v=A76t0u0pS68

Debres caught inbetween blades. Remove and clean all material for blades.