It might be worth a go Tom and thanks for the idea. The benefit of taking the cluster off I understand is that you can draw the cable out completely, clean it and lube it etc. I’m going to try and take it apart later anyway - I’ll report back! 😁Andy, found this on YouTube.
It shows spraying a speedo lube down the cable from the speedo unit. Could you do the opposite of spraying it up the cable from the transmission?