I have a lister 2 cylinder engine (mid 1970`s) with a lazy front pot, when shutting off rear cylinder(valve lifter), front pot only just manages to tickover. Without ripping engine down has anybody had any simalar experiences? Any ideas would be appreciated to try. Thanks.

Have only just seen and registered with OGA and although you have probably fixed your problem I very rarely see any references to Lister engines so thought I would share the problem I had.
I have a Lister HA2M11 air cooled engine fitted in a 30ft Gaff rigged, clinker ketch with makers plate giving build date as 1962. Have had this boat since 2002 and am still working on it although I do get out on the water occasionally.
My problem was that one day last Jan 2009 the engine would not start, turned over ok and tried to fire but would not keep going. Presumed it was not getting enough fuel.
Found that one of the injection pumps was seized, could not move the control rod, so removed the pump and washed with petrol as I did not fancy trying to dismantle it. After a few washes the control rod started to move and eventually became free. Reassembled and the engine started ok and been running fine ever since, have thought that perhaps I should have treated the other pump while I was at it!