Intro AOR AR1500

[RPZ57]

In addition to a recent Icom 'R3, I just aquired an AR1500 in a private sale. The seller I presume

Skimming the online manuals and forums I have what appears to be the basic AR1500 - as opposed to the AR1500E or AR1500EX. That is what is on the back plate, and box. Ser# 34937 on unit matches that on box. However, it has a three-pin battery connector, and what looks like the microproccessor reset switch (two wires) under some black tape in the battery compartment.

So; how do I determine exactly which reset process to use to return to factory default settings; since this differs for the basic '1500, "E" and "EX"?

Thanks for any advices.