same thing happened to me a couple of times. the best thing i could tell you would to be get new bindings, because imo the marker frees you have totally suck (i broke 2 pairs of them so fast...). Besides that i would try and mount them in a different place over just putting more inserts in because when you put the inserts in again, more than likely it will happen again.
good luck man, and have fun skiing
Completely fill hole with urethane. tap excess so its flush. Redrill hole into the urethane with bit that is one size down from whatever diameter helicoil you have. bit must be super sharp and fresh and do it slow. drill must be perfectly vertical. then take brass helicoil and screw it in slowly, then unscrew it. make some epoxy with steelwool, put some in the hole then screw helicoil back in. then put alittle more epoxy in, then put binderrr back on. you must do this very fast depending on what epoxy you use. so only do one ski at a time.
easy fix and it works well.