if there are dirty contacts at battery or stuff like that.....
Fiberglass pen or scratch brush, (white brush fibres) clean up soldering joints prior to soldering
or perfect for cleaning say battery contacts on numerous devices from corrosion dirt gunk crap or whatever
A couple of quid, easy reach into battery compartments to clean contacts blah blah blah
sure you can clean the contacts with something else, scrape off gunk, sand paper if corroded etc....
but the pen stick cleans up stuff like copper/conductive surfaces easily to improve electrical conduction
plus assists with stuff like soldering, keying the area to be soldered
(though with ultra heavy duty contacts - I'll sand the surface lightly to key it so solder sticks like shit to a blanket)
Give it a clean, give it a blow, reassemble - all working nicely once again without on/off intermittent spluttering
might be worth a look & keep one to hand to clean up all sorts of electrical contacts easily
not gotta mech so know fuck all but if dirty contacts are an issue then a fiberglass pen might help