Hi moocher,
i had exactly the same problem recently. make a small tab from mild steel and weld it on. I welded mine with the selector in place.( Needs a steady hand) make sure you cover the rest of the internals though. think this photo will help. Bit untidy, but theres no way i was gonna get my grinder in there! Don't know why my photos are enormous!?
before restorationduringafter .I,ve just recently restored a 1980 yamaha dt175 mx. Same as the 125 except the barrel of course. This was the last dt before they went liquid cooled. Handled great, although a bit top heavy, plenty of acceleration & you could jump it , but if you tried the jumps the mx boys do today you would end up in casualty with an assortment of swingarm & suspension parts up your ass.
my mudguards & tank/seat unit were horribly damaged and painted GREEN!? and they didn't even bother to mask anything up as they sprayed the seat and airbox as well for good measure!
