For the record, I rebuilt the vacuum pump with the help of the DIY pages. I stripped out one 5mm bolt and dremelled it off (replaced with a 6mm hex screw purchased from Lowes). The pump internals looked good, but one of the valves was broken into 3 pieces. I guess this is what was preventing it from pulling a good vacuum. Everything works normally now.
I hope I don't have to take that fan off again for awhile. I had just changed the water pump about a month ago...and now the vacuum pump problem. Hopefully, I can make it until spring now with no major maintenance.
