Tektronix CA PLUG-IN Instruction Manual page 26

HOW TO ORDER PARTS
Replacement parts are available through your local Tek­
tronix Field Office.
Improvements in Tektronix instruments are incorporated as
soon as available. Therefore, when ordering a replacement
part it is important to supply the part number including any
suffix, instrument type, serial number, plus a modification
number where applicable.
If the part you have ordered has been improved or re-
placed, your local Field Office will contact you if there is a
change in part number.