Well, since you're interested I'll update on my issues, problem seems to be that the outside fan isn't coming on. I crawled onto the roof and had a look, the plastic fan grill just crumbled in my hand from 18 years of sun exposure. Floor of the housing is rusting pretty badly too. It all looks pretty gnarly.
Have a guy coming out to either fix or make an offer to replace later this week. Said to expect around 1800 for a Tosot or 2400 for a Daikin including taxes, installation and removing the old one. Could save 200 removing the old one myself but at this stage (you know you're getting old when...) I'd rather pay someone to lug that thing off a ladder than mess with it myself.