stripped limit screw threads on Ultegra DI2 front derailleur

I managed to just do something real stupid. I have managed to strip the threads out of a Ultegra DI2 11spd front derailleur where the low limit adjustment screw threads in. I have removed the derailleur, unscrewed and removed the screw and looked down into the hole where the screw threads in. It is a metal screw but it looks like the screw threads into plastic. Anyone ever heard of stripping the threads out of a Shimano FD-6870 front derailleur? Is the limit screw indeed threaded into plastic? Any suggestions on how to fix or repair this? Or am I stuck with buying another front derailleur?