On Thursday, 5 February 2015 19:31:07 UTC, Another John wrote:

My old one is an Alko - had it 30 years, used maybe 4 times a year for
odd jobs (pruning and firewood cutting - not felling). It's showing its
age in various ways, the main one being that the auto-oiler failed a
year or two back (following advice in this hallowed place, I currently
oil it by dripping the oil on the sawchain every few minutes from an old
washing-up liquid bottle.)

I take it you tried paraffin to see if the clogged orifice is unblockable? Paraffin is too thin for major lube use but diesel will do OK. What it lacks in viscosity it makes up for in volume.