Spent most of Saturday and a good bit of Sunday morning trying to strip
some architrave. I normally wouldn't bother but this stuff is original
and about 8 inches wide so would be hard to replace.

Anyway, being mindful of what (lead paint etc) might lurk beneath old
layers, I've kept a close eye on what I'm dealing with. It seems that
it was stripped then varnished and has just one (fairly recent) paint
layer over the top of that. The paint comes off easily with a heat gun
but the varnish forms a sticky goo, which then sets once it's cool.

Is it just a matter of elbow grease/careful heating and scraping, etc to
get this off, or is there a more clever approach I should be taking? I
know paint strippers are a waste of time for paint, but I can't help
thinking there may be a useful solvent for this.

Any suggestions out there?