Hello dano jams. parking brake mechanisms are basically toothed ratchets that have an item that locks against the teeth locking it into position. Go under the dash and try to view the teeth and what is happening by moving all the components and analyzing what you are seeing. Check for a parking brake release handle that is keeping the lever from returning to the position that it needs to lock the ratchet. Also, check the locking tab and make sure the tab is free and that the spring that returns it into a locking position is not broken. If you find broken pieces, you may be replacing that entire parking brake control assembly. Start there and something should become obvious as to why it won't lock.
Your JA Expert,
Thanks for you response. I cannot see the teeth, so I was going to pull the mechanism out, but the manual says there are 3 bolts holding it in place, and I can only find 2.
Here is a picture of the 3 bolts. Pulling it off is definately your best way to determine what is happening. You may be able to fix the unit you have, once you see it up close.