List of episodes in which Scotty is missing:

"This Side of Paradise"
"The Alternate Factor"
"Errand of Mercy"
"The Menagerie Pt. 2"
"Amok Time"
"All Our Yesterdays" (Yet they used a voice clip)

The Alternative Factor.

Correct me if I'm wrong, but wasn't Scotty missing from these episodes as well:

"Charlie X"
"What are Little Girls Made Of?"
"Dagger of the Mind"
"Miri"
"Conscience of the King"
"Court Martial"
"Shore Leave"
"Journey to Babel"
"The Omega Glory"
"The Man Trap" (except for voice)

You're right. Missed those.

Since there is a problem accessing birth records from the years 2200-2240, there is some controversy about which of four cities in Scotland has the right to honor Mr. Scott as a native son.

Scotty only became a regular in Season Two.

you never see Scotty replacing the gaskets in the warp coils with a big spanner, do you?

Since there is a problem accessing birth records from the years 2200-2240, there is some controversy about which of four cities in Scotland has the right to honor Mr. Scott as a native son.

He mentions Aberdeen in Wolf In The Fold.

He says he's an "Aberdeen Pub Crawler". He could have been born in another city (for example Boston) and moved to Aberdeen when he was 10 or so. I doubt babies do much drinking, even in Aberdeen.

Has Scotty mentioned any other Scottish city?

Edinburgh. In STIV:TVH he claims to be from the University fo Edinburgh

Two Scottish cities mentioned. Anyone know of any more?

That happens a lot with TV characters who are Scottish. As writers change and the show progresses, the character claims they are originally from multiple places in Scotland.

These can be fictional parts of Scotland as well: _The Simpsons_ Groundskeeper Willie in one episode claims to be from a city in Scotland called "North Kilttown".

Of course, what Scotty said in TVH was probably part of his cover story.

He probably went to Starfleet Academy once he finished high school (or the 23rd Century equivalent of).

Plenty of English and Scottish universities are centuries old in the real world. Oxford, Cambridge, et al might still be around in Scotty's home era.

Cambridge is still around in the future, we saw in the TNG finale, All Good Things.