The Marshall CS JTM 1 carries a tube/valve complement of two ECC83/12AX7 in the preamp and one ECC82 in the power section. Once the tubes have been removed for replacement, how does one tell which tubes go back into which sockets? The pin outs allow for any of the tubes to go back into any of the sockets. I can't seem to find a PDF of the ower's manual either. Is there somewhere on line that Marshall or another source provides this PDF? Thank you for any  help in advance.