The right-side mirror mount on my Paladin 150 does not have all the threads. They are only on one side for some reason (how is that even possible?!). Needless to say, it's impossible to screw the mirror in like this.

I measure the mirror threads at around 7.75mm with 1.25 pitch so I figured I could use an 8mm-1.25 tap to chase the threads but after testing the tap on a piece of scrap the mirror seems too loose so I think it might be too big.

A 7mm tap would probably be too small. I have never seen a tap in the 7.5-7.75mm range. Anyone know what is going on? Is it maybe 1.00 thread pitch?