I have a Honda HRX217HXA mower where drive wheels have progressively slowed. Recently after each use I've notice oil on the garage floor underneath the transmission. I wiped clean, rechecked and see it is seeping from the shaft seal on the left hand side of transmission housing. I set mower on end and removed one of the plugs on the transmission housing, added some Honda 08208HST01 hydrostatic oil and retried speed. All worked good, wheels engaged and speed was back but oil leaks too rapidly. I feel pump is okay and just need to replace seals, ref attached item 15. I know transmission has to come out to replace question I have is how difficult is it to replace the seals? Any tips on how to remove old seals and install new? It appears only one is bad, once I remove transmission is it recommended to replace all three?