The blow-torch/heating method is unnecessary. All you need is to get a long rail like this:
Then get a non-slip plate, e.g. an Arca-swiss type plate for a Nikon DSLR. Attach it to the rail, then attach the rail via the plate to the Markins Ball head. Orient the ball so as to drop the attached rail into the notch (for vertical shooting), tighten everything down, then grab the rail on both ends with both hands & turn counter-clockwise. The rail should provide enough torque to unscrew the quick shoe from the ballhead.
This also avoids the issue of removing the spirit level, which I was unable to do. In fact, using an Allen Key to remove the level resulted in an utter mess, as the level broke, & it's almost impossible to remove its remnants from the hole in the hotshoe (it seems to be made of epoxy or some other plastic - I've been trying to dissolve it using acetone, with limited success). I don't know if they changed the design of the level, but it is definitely *not* possible to remove it via an Allen Key with the newest Q3T...
Hope this helps.