Disconnect the probe from the instrument and measure the resistance between the probe body and the red wire. Also measure between probe body and yellow wire. ‘Ungrounded‘ probes will show ‘open‘ circuit. ‘Grounded‘ will show around 1 + ohms.
Scanner units built after 1986 are grounded.
SN’s less than 1400 are ungrounded.

There is a screw adjustment hole on the bottom of the instrument. Will need a small screw driver to fit into this hole. It is a 10-position switch. Set the unit to the highest numbered probe and turn the screw adjustment until the front panel shows the number of the highest desired probe. Switch can be turned through 360° without damage.

Top row EGT. Bottom row CHT
6      5      4      3      2      1

Yes you can. The ‘older’ Classic Scanner used ‘solid’ thermocouple wire with its set screw type connectors, but you can use the new JPI ‘braided’ thermo wire too. Just call the Sales Department at JPI for the price per foot. 800-345-4574.