Hi Terry,
There are many web-sites that can provide basic information on how to true wire rims....Here's one:
http://www.gomog.com/allmorgan3.html
If you use your providers SEARCH engine, just enter something like HOW TO TRUE WIRE RIMS and a lots of sites will come up, most pertaining to bicycles but a few for automobile wheels like the one I provided above which is a MORGAN auto site.
IMPORTANT: Some Shay's came with adjustable spokes and others not so it would depend on the type you have.
If your "out of balance" is minimal, I would think a good shop that balances wheels could fix your "wobble"....Remember, if you go the balance route, have the shop put the weights on the INSIDE of the rim so not to blemish the outside...A good example are my rims which were balanced and then painted over the wheel weights????
Hopefully, someone else that has a Shay can provide more vivid and detailed information.
Reggie