HAHA Success!!!!
First of all a BIG thank you goes out to Pete for a fantastic guide and lots of assistance.
I guess a little persistence goes a long way - after much struggling and much pulling and little knowledge of what I was actually doing, I finally managed to get my clocks out today!!!
I did as Pete suggested, removed the undertrays, undercover and had access to the speedo cable.
The speedo cable only actually had one lug on it so was a pain to get off but with a little force came loose. The power adaptors on the other hand, did not want to budge! Finally got them out..
Vacuum cable was securely attached and I dont think this was the issue..
Even with my little corrado steering wheel I managed to pull the clocks through the hole and to freedom!
Going by Pete's fantastic comparison pics I indeed have the later clocks with the later speed sender.
I took it apart and the top pin of the three (edge closest of the 2 together) seemed a little hampered in connection but overall it looked ok to me.
I bent them in and out and re-attached them to the clocks.
Havnt had a chance to fit it all back together again yet as it got dark and was dinner time, will give it a go tomorrow .. no doubt will be just as much of a pain to go back the other way!
Should I look for anything else while I've got it all apart...?
Thanks again for all your help Pete, fingers crossed it works when I plug it back up!!