I found a video with an external hold down to work in place of the internal tab if it's been broken off.
I made one myself for a triple enthusiast that had a broken tab o his S1 oil pump. A short piece of tubing, a 1/16" ( 1.5 mm ) thick piece of sheetmetal and a M5 x 45mm bolt looks like it will do the trick. The sheetmetal needs to just clear the top of the cam bolt with it pushed down. That will allow free movement.
Any interest in making more of these?
Jeff
Attachment:
oil pump hold down top.jpg
Attachment:
oil pump hold down side.jpg