Was just stripping the frame for some cleaning and painting. Four of the threaded inserts on the frame started spinning freely with very little torque. Thankfully they weren't holding anything on, so it's just the bolts stuck in them.

Used some penetrating fluid and pliers, but no luck. Any ideas for removing the bolts besides drilling them out?

Any way to repair or replace these inserts? Quick search didn't turn up much, but I have a feeling I'm not using the right terminology.