Make sure you get the manual, some have supplement books
This one restored, recalibrated
https://www.ebay.com/itm/324626522534?hash=item4b953fa1a6%3Ag%3AwGEAAOSwly1goJvG&LH_BIN=1
This one restored, recalibrated
https://www.ebay.com/itm/324626522534?hash=item4b953fa1a6%3Ag%3AwGEAAOSwly1goJvG&LH_BIN=1