The plug on bullet is the drain/fill plug. There is a vent plug on the
side of the drive near the top where the decals are. To check it loosen
the lower plug enough to let 1/2 oz or so drain into a small container
then tighten the plug back up. Watch carefully to see if any water
comes out before the oil. Water=bad. Examine the oil. Cloudy or
brownish or whiteish=bad. Shiny flecks in the oil=bad. The oil
shouldn't feel gritty if you rub it between your fingers.

To check the level, make sure the engine hasn't been run for several
hours. remove the vent screw and watch for the oil to be at the bottom
of the screw threads and maybe dripping out just a little.

For refilling, get a pump kit from your dealer and refill thru the
bottom hole. watch for the oil to start coming out the vent hole then
stop pumping. Replace the vent screw, then quickly remove the pump and
replace the drain screw. This part of the job can be messy if you don't
work fast.

It takes a quart,maybe a little more, to fill an alpha 1.
Hope this helps,
Jim