Ricoh C751 Toner Pump

Good day all, please advise what is the purpose of the hole that is identified in this Photo. Its the Toner Supply Sub Assembly Pump. we are experiencing a toner supply issue that the print had a reduced color due to toner shortage. we cleaned and checked the supply hose and allis clean but the pump seem to have so little suction. If the pump is cleaned thoroughly does this covered hole has a particular role to play. Please advised.

 

We did some more test and noticed that the voltage to our pump is 0 even as we run SP 3050 which is force toner fill, What controls or send voltage to these pumps? we did check another color and that one get the 24Vdc during the SP 3050. Can anyone please help!