I wonder if its a steel wire inside the cable where you can weld it together and lubricate it. I'm probably wrong. (i haven't taken out the dash out on mine)

Thanks LONGBROW. I'll give that a go and see what happens.
I took it for a drive to the weighbridge to get it weighed and found the speedo was all over the place.
(BTW....car weighed in at 820kg with no interior, 34kg rollcage, front seats 6kg each, Celica box, A15, twin 45's, ute diff & TRX rims. I think most of the weight was in the TRX rims....those things are rediculously heavy compared to other rims)

If the cable is at fault, I suggest you disconnect the cable at the txmsn, ensure it is clean and not damaged, and reconnect it. You can do the same to the speedo connection side,but try the txmsn side first,as it is easier.

Anyone know of a cure for a bouncy speedo needle that won't stay on the correct mph.
Is this a replacement job or will greasing the cable insides work..??
Anyone else had the same problem and a certain 'fix' worked.
Thanks.