Speedo cable dilemma

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Hi there,
Any help would appreciated with my hurdle.
I am attempting to change out the speedo cable on my 1982 KZ250 but am having trouble removing the wheel end of the speedo cable. The manual says that if I was to install a speedo cable, at that end, that I should insert the speedo inner cable into the speedo gear housing while turning the wheel so that the slot in the end of the cable will seat in the tongue of the speedo pinion. Im thinking if I spin the wheel while unscrewing/ pulling/ tugging/ yanking etc that it would just slide out.....but its not. I know I am doing something wrong but can not figure it out. I have cut the speedo cable in half because it was giving me the sh its!

A picture might help

It looks to me like that screw or pin below the cable is what locks it in place.
If it were me I'd take the wheel off and pull the hub.
There has to be something that holds the cable in place, a pin or clip or something.

The end of the cable is just a small fork that slides on to a tongue on the speedo pinion.
When installing you just turn the wheel or turn the inner cable so the tongue fits in the slot.

Clymer manual?

Brakes. if you don't know the age of the brake shoes, replace them. The adhesive gets old, so a lining can separate from one of the shoes and get jammed between the shoe & drum, locking a wheel. It would be a real drag for it to happen at the rear, possibly catastrophic... more so at the front. Replace both sets, front & rear.

Probably rusted together. Don't know what to recommend there other than the usual penetrant spray like PB Blaster and keep trying.