Help - 9f chassis broken

[MasterCutler]

I've had a metal failure on my Minitrix 9f. After dismantling for cleaning/contact adjustment the rear threaded pillar on the chassis split when being reassembled. The instrument driver was being used between finger and thumb!
Does anyone know the thread used on these - I'm guessing its metric not BA. I think there's enough metal left in the chassis to tap through, and make a separate pillar as the drawbar pivot.