[Sean Hamilton]

Hmm, from my experience door latching issues on older cars are a symptom - the actual cause is usually the hinges (worn) - not the latch.
You could end up chasing your tail - realigning the latch to an out of whack door fit?
I'd check the hinges first - door fit panel gaps - has the door dropped a wee bit? Does it move up and down on the hinge pins?
A temp fix is to pack between the hinge plate and door with gasket paper to elevate the door back up to realign with the latch.
I think Wayne may have covered this topic more or less in his 101 book?