Shimming the inner primary is a very important step that often gets overlooked. On my 73 850 I knew that it needed to be done to cure a small annoying leak just like yours. Nothing major, but it was the only place that any oil would make an unwelcome appearance. Hylomar would work for quite a while, but eventually a drop or two would crash my party. Being on the conservative side with my personal energy expenditure ( my wife calls it laziness) I didn't want to go through the major hassle of pulling off the inner primary. Something else always seems to crop up or go wrong. So I took my shim stock, fender washers of various thickness, and cut a 3/8 inch slot so that I could slide it over the mounting stud without having to remove the inner case. Got the slight warp out and kicked that bitch leak to the curb. 5,000 leak free miles including a one day 700 mile freeway blitz. I celebrated by ordering up a milled from billet primary from Matt at CNW. Motoporn!