You need to check them from above, I'm afraid. It's a real PITA to get to them on the later cars, might be a little easier on a '79? I'd see what folks here say.
I've done the job on my '63 and '74 which aren't too bad. The '91 would be a %&*$, and I suspect yours is somewhere in the middle.
Well, it looks like the gearbox will be coming out again. Anyone know of a good Alfa mechanic in the Hamilton Burlington area of Ontario? I know of Pinarello Mortori in Toronto, but they are difficult to get to (more so for my wife who would have to pick me up once I dropped off the car).