We're currently enjoying a strategic retreat and regrouping. After half an hour (including three smoking breaks), he came to tell me that he was having problems, because the shop told him to put too much oil in BNPM, and he should have followed his own instincts, because it's clogging up [some widget or other] so he needs to get a steel brush to clear it. He's coming back at teatime with the brush and then he and BNPM will complete the campaign. I did mention BNRBM but he rejected the need for reinforcements.