I had my turbo apart for some modification. I marked the compressor wheel and shaft but in reading the Holset workshop manual it looks like I should have marked the slinger too. Is this nessecary with a turbo of this size? Also, I am trying to tighten the impeller nut and I haven't been able to get it torqued without the compressor turning in relation to the shaft. Does anyone have tips on how to keep the compressor wheel from turning?