Electron Multiplier

If you are requesting help, you really need to be a bit more explicit in what you need help with.  If you refer to the manual there is a detailed section on how to replace the EM, the only caveat would be if you switched from the original style of horm to a mulitchannel type multiplier which uses a different mout.

Figure out what exactly you do not understand and then reply back.  Remenber that none of the people that reply to these posts are paid for it, we do this as a service to our colleagues.