Mileometer woes

[l10tus]

1994 Chimaera Mileometer battery has failed.

Here's where I'm upto:-

A) Removed dash top

B) Disconnect two small lamp holders and the four pin plug from rear of Speedo.

C) Remove Speedo from dash tinware.

D) Prise off folded bezel, remove glass.

E) Remove two 4BA retaining nuts and washers and two screws

F) Remove CR2032 button lipo and replace with dummy battery and extended wires, through new drilled hole and rubber grommet in the rear of the Speedo case/can.

G) Purchase CR2032 battery holder (Amazon UK £4 for 10)

H) Insert new CR2032 battery into remote holder and connect a 12vDc external power supply and signal generator (eBay £10).

G) Power up generator to re- clock the correct mileage.

However question is:-

Which wires to connect to the signal generator (the 4 pin female sock only appears to use 3 of the connections within?)

Which signal to use on the generator ( square wave from?)

How to wind up the amplitude, to re-wind 61K miles onto the mileometer as quickly and safely as possible?

Please can anyone who has actually done this repair, respond with correct way / any tips, to do this?

Not really interested in "well I thinks" Please!

May thanks,

Phil.