hi all i have a 115 mercury 2 stroke outboard 1997 the power trim leakes on the down stroke and when motor is all the way down i hear air bleeding out. from the up postion when i trim motor down it leaks from the top of the ram.(o rings i guess) but cant find any rebuild kits cant find and part or serial numbers on unit. (prevouis owner kept boat in salt water ) so cant make out any numers any help would be great thanks