Dealing with a stuck JIS screw

[michael1954]

Went to bleed the brakes on my CBR250R and one of the cover screws wouldn't budge, even using the proper JIS screwdriver. It started to cam out and displace metal in the screw head.

I decided to get a ball-peen hammer and carefully beat the protruding metal back down into the screw head. This made the screwdriver fit very tightly and I was able to break the screw loose by momentarily turning it clockwise and then counter-/anti-clockwise.

This is the screw after I loosened it:


Looks like there's some galvanic corrosion happening between the screw and the cover, so both will be replaced with new + a small amount of anti-seize compound.

This method was less scary than a drill and a tiny back-out, and saved the master cylinder itself from being damaged.

I replaced the phillips screws on my reservoir covers with star-pattern screws I got off ebay. They work a lot better. Tighten easily and remove without stripping. If you are interested I can find the seller on ebay.