Hi T.O.M. Need your help or anybody that could give me a solution. I have been adjusting Walbro carbs for years and my Trusty "Pressure Pop-Off" unit #500-505 does not hold pressure. It appears the Flapper valve is worn. See Picture. I can purchase a new unit for over $200 from Walbro and $80 from a distributor. I had hoped to get a Re-Build kit but it appears there isn't any. Does anybody know if I could get a replacement valve or re-build kit? Any help would be appreciated. Col. Chuck Winter