I used to do that with 480 volt 3 phase SCR power packs, clean all the parts, replace the SCRs then reassembling them... all off of drawings I did as I disassem

I used to do that with 480 volt 3 phase SCR power packs, clean all the parts, replace the SCRs then reassembling them... all off of drawings I did as I disassembled them. This in the era before digital cameras and internet. Let's see those put back together, working. ;-)