What Pete says. Only in the spirit of being helpful, of course, make sure there is oil in tank. You might also want to remove oil pan drain plug, see what comes out, hopefully about a pint or so of oil. Then add a pint or so of oil thru tappet cap, it will run down to sump. To answer your question, when engine's running, remove cap on oil tank, shine a flashlight in opening you should see oil coming out the return. If not, then you may consider if tye return oil line collapsed, i would think unlikely. Before assuming it's something major like oil pump failure, check all the smaller details. The pump is a trochoid type, they are trouble free. Unless something has cme loose. It sounds like you had oil pressure just fine, so something happened. Either no oil, an oil supply problem or pump is not returning. Make sure both oil lines are patent.
