It's not the belt, it is both present and not chirping.
Air is doubtful due to a wheel lock.
I pulled the reservoir last night and while there was hose debris, a thorough cleaning of the 'filter' portion yeilded less noise, but still a lot more noise than was normal.
I'm going to order the pump today and get it swapped out.
Oh, and a really good way to clean out the reservoir is with a turkey baster. One with a slim neck worked well and within a few minutes I had the whole thing emptied. When I took the hoses off I was also able to suck some of the fluid from those too so I had less of a mess.