Dont know if anyone can help.

My locks have been getting stiffer and stiffer over time and I've been trying to lube them up but recently the key turns but the car no longer unlocks or locks.

SO

I dismantled the door and discovered the problem was the little plastic arm on the back of the lock barrel it has a square locating it on the end of the lock barrel but that has worn and rounded.

Does anyone know if they are still available from Ford ?

Used on other vehicles of a similar vintage ?