I am using an AKTA Prime Plus. The pump works, but the pressure stays at zero, and no liquid is running. I suspect there are some bubbles, so I want to purge the pump. I read the manual from Cytiva, and it shows how to insert the purge kit into the pump (see picture 1). However, my pump does not have any hole to insert the purge kit; there are bolts in that position (see picture 2, red cycle). Has anyone else faced the same problem?