those keen serts are the best fix, helicoils suck. try looking up time serts they are similar to the keen serts, maybe less exspensive.
if you don't want to spend $ drill and tap the holes to 10mmx1.25 install a bolt with Loctite cut it off and drill and tap it to 8mmx1.25 . I have done this fix it takes time though to get it rite though.