2000 ts astra cd tacho not working,

So,now my Tacho not workin after many issues have been rectified including
Abs tc lights coming on and speedo clocks stopped
Pclip test showed hub needed changing so did that myself and changed all cables checked connections ect reset with scan tool and still there, so changed abs control module all good no more problems till recently did rocker cover gasket and inlet manifold clean then car ran perfect except no tacho now? Have had dash pod out numerous times so am aware of potential bad connects / grounds and have checked all obvious things and comes up fine... have also changed cam and crank sensors from working cars to no effect? Thinking gotta be ecu? If so can a second hand ecu xfrom wreckers go strait in if, and i say if? I get ecu immobiliser reader and contol unit and the rfid tag from the key, will it all just clip in and start?
Have done everything myself up to now with no problems but not sure how to test ecu with multimeter for faults, andwith no shortage of second hand parts available to me, not sure how to proceed from here any help appreciated massively!,
2000 ts cd astra manual x18ze

Tried swapping in a new cluster?

yeah put a new one in ( wreckers sourced ) but no change.. getting little bumps on the speedo where the needle will jump or drop over bumps in da road, but other than no tacho, its exactly the same as before!! thinking bout it am not sure if i hahve the right globes / fuses in the display? r they volt / amp specific? ie less volts /amps limited functionality p codes coming up! alternatively would too much also fry the clocks or cause errors?

Did you end up finding what the problem was? Mine is doing the same thing