Replaced lower seal on my LB F engine. After 15 minutes of use I noticed it had worked its way off and slid down the shaft. Reinstalled after cleaning the seal area below the bearing and used some Permatex hard setting sealer to attempt to keep it from working out. I found that it again slid down the shaft. Maybe the seal it undersize? Got a pair off ebay from a small engine supplier...maybe aftermarket item rather than OEM. The seal has a blue coating around the OD. Anybody had this happen and any advise before I try a third time to install the seal. Obviously the fit is too loose in the housing. I used a thin-wall steel tube to tap it in which worked well. Thanks for any replies.