So I've replaced the EZ Wheels on my M6R with 76mm skate wheels, but for some reason one of the bolts keeps loosening and threatening to fall off.
I can't figure out why a single skate wheel has almost fallen off like 4-5 times while the other 3 wheels are still perfectly secure. All the bolts and nuts were purchased brand new - 2 x M5 and 2 x M6 - at the same place with the same specs. They were fixed with the same number of reused washers on both sides.
I'm sure there must be a perfectly common explanation for this somehow, yet I can't think of it. Any suggestions would be appreciated - especially if it doesn't require extra $ like buying Loctite.