Riders of Bristol.
DO NOT replace the cover as it won't match the crankcase.....reason the seal keeps leaking is because you're not fitting it properly.
Did the drive gear break up ?.....if so, make sure you get all debris from the swingarm and lines.
I changed the oil pump last year cos it was leaking bad at the angled down union on the front. When I got the old pump apart both gerotors were cracked, no bits though really. I took some photos of the drive gear and it looked and felt OK so I put a used pump on and went to the IOM I've done less than 1k miles and this pump it gave up when I was nearly home last week about 5 miles.The pushrods were rattling bad. Pump apart and I couldn't turn it by hand, a fair bit of small debris in this one. Gerotors all narled up and the top of the drive looks worn. I've probably fucked it, time will tell. Thanks for the heads up on the cover.