to be honest the best thing you might want to do, as the end user
is hire a reputable professional to diagnose the machine properly and repair it

inherently these machines can pose a danger to you working on them, (if you do something wrong they can "run away" and cause personal injury and property damage)

you normally dont clean these contacts with a spray cleaner
you would take them apart and clean the tips with a clean file,
rebuild with new contacts, or completely replace the unit

normally i wont do any of those things before i was 100% sure the contacts are my issue

if i remember right the glue giant uses a model that isnt exactly meant to be taken apart or serviced (curtis/albright)

wd40 isnt a cleaner (though some use it as such) its a lube
to clean electronics you would use a NON-conductive electrical cleaner, but in this case that harsh chemical may damage the plastic housings

furthermore the contacts may be ok but the moving parts may be binding or bent

it would probably save time, aggravation, and possibly money by hiring a tech

maybe someone on the board here in Cali will see the post and be able to help you out