Man, what I wouldn't give for a water aspirator at this point. I suspect Dan was referencing a screw-into-the-faucet old school water aspirator. I mentioned this in passing to my boss (as in 'ya know, even a water aspirator would pull better than the house...') but was shot down. 1) it wastes too much water and 2) if vapors don't get caught and re-condensed in the cold finger, we don't want solvents going down the drain. So that's out.
If there are any leaks, it's between the tap and wherever the actual vacuum is. There's only a short section of tubing from the tap to the rotovap. It's definitely a building-wide problem. All labs complain of the lack of adequate vacuum.
A diaphragm pump would be really nice. I know that new they can be quite expensive, but I've never tried to look look for a used one. We're a small-ish department in a small undergrad university, so we don't have oodles of funds. If I ever get my own grant, maybe I'll buy one for myself.
Today, we did ok with getting 'most' of the EtOAc off with the house vac, then pumping the last of the solvent off on the high vac manifold. There was one column fraction that was ~125mL. We left it on the rotovap over lunch (which is probably what I would have done in ideal circumstances, anyway) and most of the EtOAc was gone at ~45degC. The high vac did ok with the rest.
I think I'm stuck making the best of the situation at hand. If anyone knows any other tricks or workarounds, that'd be awesome. Thanks for the advice so far