Scorpion traveller Tacho / ignition module

[Lostcause]

Hello!
I have been working on a mate's 2002 MZ Scorpion Traveller & the rev counter does not work!
He bought this bike in poor condition & a bit of an unknown so I'm not entirely sure if something has failed to cause this issue or if it has had incorrect parts (ignition module) fitted.

I purchased a second Tacho (in very good condition), both of these have the number: OP-0249-002
(Neither work on the bike)
The ignition module has a blue label with: 3YF-82305-00

So firstly I was wondering if this pairing is correct as I have seen mention of different ignition modules & rev counters (& not being interchangeable). Plus any ignition module I can find advertised for this year bike has the number: 4MY-82305-00

Also there is 12v getting to the rev counter, the ground is good & the signal wire to the ignition module is good.
Any idea what I should have at the signal wire?
And any other suggestions?

Many thanks!!

*Update: I bit the bullet & purchased another ignition module (an orange label 4MY unit) & all now works properly!