primer bulb

have a mid 90's Craftsman edger that has a 3.8 hp Tecumseh engine. The primer bulb is a 36045 primer bulb. I think in maybe 15 years I have replaced it twice - the last one came from maybe Jacks or Tulsa Engine - just a red bulb held in by a ring. This engine has been really hard to prime and if I hold the ring in with a small screwdriver and pull and pump the bulb the engine will get enough fuel to start. But if I just pump the bulb there just isn't enough fuel to get it going easily. I ordered a new bulb today, a new old stock packaged one. I am thinking that maybe the bulb leaks air around where it seats. Is there anything I can put on it when the new one goes in that will help seal it? Are there any other parts that might be at fault? I have gone thru the carb and it runs well once it starts. I don't see any check valves for the bulb. I was thinking maybe some HD yellow 3m weatherstrip glue might help but I suspect some of you have run into this before.

I will post an answer to my own question. I went thru mu spare nos edger parts and I had an original 36045 new in a Tecumseh box. Pulled the generic red one off and put this one on. The red one was even leaking fuel when I tilted it sideways. Put the new one in, seated it with just the metal ring using a socket of the right size and 1st pull it fired up and ran without multiple pulls. question answered.

Thanks for the follow-up. It's always good to see what the resolution of problems was.

I did some edging, let it cool and needed to prime it to get it going - works like it did when new again. Also runs stronger and doesn't die two or three times while trying to get it going. I noticed that even though old stock, the nos black rubber primer is softer than the red generic replacement that everyone sells. The small metal ring that holds it on the NOS one is blackened spring steel instead of the softer bright steel. That probably helps too.