I was thinking during the run, did 3/4 qt go into the filter? With that pan 4qts should be in the sump (actually with the correct stick/tube it should be reading full or very close to it with 4 qts on level ground). Did you have close to 4qts in & what was the psi before/after it changed & if not I'd go ahead & get it to full (4qts in sump) & retry it