Basically, you want the spark advancer to snap back really good when you turn it and let it go. I took mine completely apart and cleaned it with a degreaser, but you can probably get away with just hitting it with a toothbrush and degreaser while it's still together. If you do go the route of taking it apart don't lose the springs, they don't make them anymore! I used Remington dry lube spray on the pivot points and it worked like a charm, it's made for guns but it's held up so far on the bike. It might not seem like a noticeable difference in it's snap before and after but it does the trick. I wish i did this first, it would have saved me a lot of time messing with cables and chasing my tail.
You'll have to re-do your timing after you put a everything back together but if you put a mark on your points plate where it was it should put you in the general area of where you want to be, check with a timing light to confirm. I changed my points when I cleaned mine just because I was going to be resetting them anyway. Hope this fixes your problem.
