I am restoring a jap 4/3 engine for my Auto Culto Mk. 1X machine, The exhaust guide was particularly worn and had to be replaced, Using a drift, I could not budge them at all and worried about cracking the cast iron cylinder casting, I looked online for ideas, and found a chap demonstrating this method, You thread the old liner internally using an 8mm tap, then using a threaded rod at least 3″ long, you thread this into the liner, over this you put a short piece of stout tube at least 2″ long, with an inside bore of 1/2″ or more, on top of this, a stout washer and finally a full nut, when you turn the nut clockwise it will drag the liner out no problem without damage, my only comment is that try to use a high tensile bolt or threaded rod if you can, I stripped the thread on the first nut but the second worked a treat, This may be old hat to the experts out there, but I found it very useful. Plonker