Vacuum System Valves

So, I have a Becker pump vacuum system for my table. I recently completely re-built the table of the machine I bought used, and I went from pulling maybe 10" of vacuum to almost 25" with a freshly skimmed spoilboard. Yay!

In the process, I re-zoned and re-did all the plumbing. However, since completing it, the PVC valves have become almost impossible to open and close. It takes everything I have to do it, and that's ridiculous. I have no idea why they've become so hard to turn, and was wondering a) if this has happened to anyone else, and b) is there anything short of replacing them that can fix this problem?

Thanks in advance.

I've had this problem with the RV dump knife valves on my 7 zone table. Hit them with some lithium grease (spray can) and they all work REALLY well now. You might entertain the same approach and it will solve your problems.

That is an amazing increase, what did you do to increase vacuum that much?