i've snapped an 18RG tensioner in exactly the same way before. Was royally pissed off.
Solution was - hammer and sacrificial chisel.
using the chisel and hammer, lighting tap the part left in the head to rotate it, trying to tap it from different angles to work it loose.
Eventually it will come loose, and you should be able to remove it using some pliers or vice grips.
In fact, looking at your pic you might even have enough meat there to get a set of vice grips onto it.
Bookmarks