Owen_Dyneto wrote:
Yeah, it's in kind of a poor location, though not much different that some other makes using the same unit, that's one reason the remote fillers were so common. Checking fluid and the like is really much easier if you temporarily remove the short length of fresh air duct.

When restoring a car to service that hasn't been regularly on the road and serviced, it's best to assume everything in the entire brake system needs to be evaluated closely. I wouldn't even think of scraping goo out of the BTV, remove it - it almost certainly could not be restored to reliable service by just scrapping goo and refilling.