Less than 50K orig mi. It'* for my dad. Bought it from our long-time mechanic. It was his fathers (Ed). Ed was 1st title; b4 that dealer'* wife drove it.

Handwritten note of oil change in 2014 at 45K. It'* been sitting around. There was some hard shifting in low gears. Mechanic changed all the fluids, etc. plus had it detailed for us. Took possession 2 wks ago.

We fixed the drivers side mirror (brown, dbl image) & reset the "low tire pressure" light.

Grrr. Now other things popping up:

AIR BAG LIGHT STUCK ON
Tried 2 area shops but no codes. Our mechanic is 1hr away & we haven't been able to get there. Trying to avoid dealer.

DRIVERS POWER SEAT "UP" MOTOR STOPPED WORKING
Need that--sadly, we are short-ish

HARD SHIFTING IS BACK--sometimes
seems like it'* after it warms up

GOOD REPAIR BOOK TO PURCHASE?
prefer good visuals

Ideas? What do I need to watch out for?

My dad is a super persnickety guy & I'm not his favorite kid, so I'd like to make it as nice as possible before I turn him loose with it. He likes me well enough, but still . . . I ain't his favorite. Thanks!

You'll need a dealer to scan to find out the airbag issue.
Has the floor ever taken on water?
Specifically the front passenger seat floorboard?
Pretty sure 94 and up had the air bag control module under the passenger seat carpet..

The seat motor'* nylon gears probably sheared a few teeth off on the shafts, you can get to the motor and get a socket ot it I have heard, and wrench it to a good height and leave it, or try a local pick and pull, GM Dealers want like 1,000.00 for the motor, and online cheap dealer parts list it around 600.00.
A salvage yard may have one for like 50.00
You will have to remove the whole seat to work on it, after removing all bolts it should tip from the back towards the front, may be 2 clips on the front.

A good repair book IMO is always the FSM, Haynes manuals suck, there is no substitution for the FSM IMO.

2002 Buick Park Avenue Factory Service Manual - 2 Volume Set