Bearing Plate Bolts

I stripped down the rear pinion gear cover of the shaft drive tonight to see what the grease was like.

Unfortunately, I snapped off one of the six bearing plate bolts. Annoyingly, part of the bolt is no stuck in the thread! I guess I will have to try and drill it out.

What type of bolt do I need to replace it? I know the top is 10mm.

Many thanks for any help.

The bolts are M6 x 15mm with a built in washer. I would recommend replacing these with good quality high tensile or stainless steel ones with a separate washer. The Yamaha ones are low quality steel thus why one sheared off.
Be careful when drilling out broken one, dont use too big a drill and it may be worth buying a screw extractor which has a spiral thread that grips the screw. You may be able to remove it by tapping the square tang of a file into the hole, plenty of easing fluid & maybe a bit of heat to expand the alloy. Do not try to fully drill out the screw as you will inevitably damage the thread in alloy casting.