I'm happy with the resolution here and feel that Scanwest did great. They also replaced the shifter bulb for parts only, no labor; performed the diagnosis for free; and did this as a walkin overnight. so, great job.
The only thing I'm still puzzling over is this: ever since we bought the car at 70k, the transmission has always been hesitant to engage. As the car aged, it became even slower to engage, and developed a notable, distinct 'CLUNK' as the gearing set.
Now with the new alternator, the transmission's hesitation HAS VANISHED. No hesitation. No 'CLUNK'. The transmission operates as, I guess, automatic transmissions are supposed to operate, although as this is my first non-stick, I actually don't know what to expect.
So here's my question: how can changing the alternator have affected the performance of a mechanical part like that? Does the alternator play a documented part in the transmission? If so, why on earth didn't a single experienced Subaru mechanic notice that issue and observe that the alternator might be the issue?
If it's not the case that the alternator has a known role in transmission performance, should I ask the shop if they went above and beyond and turned a bolt or something in the transmission along the way? It's definitely not on the statement I have in hand. Anyway, I'm definitely not complaining, just pleased and mystified.