On 01/19/2013 7:00 AM, David C. Partridge wrote: The zener token value is written on the lower right PCB in the rear right hand corner. I should have remembered that. Thanks for the reminder. BTW, anyone looking for cal keys, the switch is still made and you can order one from several of the online suppliers; I got mine from Digikey. The part number on the switch is current. (or was last time I checked) It wasn't particularly expensive, either. One note - the switch has 32 (or so) possible keys. Solartron always used the same key. But, if you order a switch, it's possible that its key won't be compatible with other Solartrons. You can specify the key, but Digikey didn't stock the one Solartron used. Personally, I didn't worry about it. -- Bill Ezell ---- They said 'Windows or better' so I used Linux.