Go on ebay and buy a rebuilt distributor, which will include a new or working vacuum advance. I got a completely rebuilt distributor for around $75, remanufactured by Arrow. Rock Auto also sells rebuilt distributors, but you can probably get a better deal on ebay. You will probably find it in an ebay store, not for sale on the auction portion of the site. PM me if you can't find one. Mine was rebuilt with all Denso parts.