Knight Model 400A Vacuum Tube Tester Checker -Partially Tested

Description

Knight Model 400A Vacuum Tube Tester Checker - Partially Tested
Only partially tested it and some lights go on. I don't know how it works but I plugged in small tube in one of the slots.  I put all the switches to P one at a time and the light went on when numbers 1,4,5 and 9 were switched to P (as shown in the pictures).  I do not know what that means.  Selling as untested.  May or may not be working correctly.
Has wear, scuffs, scratches and one of the knobs is bent (but still turns).