is there any way to soften up old vac pot seals?
There is a thread out here somewhere with a big discussion of that. The gist:
1) The rubber gets shrunk and hardened with 'glaze', which can be removed with certain solvents.
2) Most of these solvents are not really intended for use around food, and some are pretty nasty.
3) At the same time, many of these solvents are used in the manufacture of these things in the first place, so caveat emptor.
Alternately, you can use food-grade silicone grease (like they use on soft-serve ice cream machines) to make a good seal.
http://www.rtxs.com/xcart/product.php?productid=16152