Hello Martin,

The jaw adjustment screws are held in place between two jaws of a hard plug inserted from the back of the chuck. In one design these are held in location with a side screw, fitted from the back of the chuck, locking the plug in position. Unscrew and tap the plug out with a slim pin punch acting on the visible face beside the waist in the jaw adjusting screw

A second design dispenses with that arrangement and in this design the plugs have been pressed in and these are rather more difficult to remove. They have to be driven out with a slim blade shaped tool acting on the face of the jaw, it has to be slim to work in the space left available by the waist of the adjusting screw. The width should be equal to the face width of one jaw to give it the maximum cross section to work without buckling

Support the chuck on something solid but with space behind each of the plugs to give it somewhere to go as it moves. Heat at each position helps in expanding the bore and gently tap each plug out, remembering that they are hard and therefore prone to chipping. Once the plug has moved sufficiently it is possible to grip it in a slide joint pair of plumbing wrenches and wriggle it out.

Regards Brian

Edited By Brian Wood on 04/09/2020 14:11:24