Old Harken furler keeps losing tension

[sharkdiver84]

I've watched all the videos available from Harken and read their instructions and they all refer to a lock nut and star washer that should prevent the drum housing from spinning and loosing up the turnbuckle.

My boat doesn't have that. I don't know if it's a different model or some kind of retrofit, but it doesn't seem to work. I have a round bronze disc that is threaded onto the stud and comes into contact with the round bottom of the internal rigging screw. They are secured together with two bolts.

I've found this makes no difference at all. When the drum spins, it spins this nut with it no problem.

Running out of ideas here. I don't see any place that would engage the star washer, unless it just holds with friction to the bottom of the rigging screw. And wouldn't the rigging screw just back away from it anyway?

There was a wire attached to the screws that holds the drum, and I used that to lock it for a while until the eyes ripped out from the load. I'll probably rig something like that again as a safety, but need to solve the primary locking first.

I guess my last idea is to try to have another disc nut made with the opposite thread so that it will jam the rigging screw in either direction when it tries to move. Just thought of that, so if it's impractical, sorry, I didn't put much thought into it yet.

Guess I'm just wondering if anyone else has seen these and how they are supposed to be properly secured. And how important is it? In theory the drum housing shouldn't have much torque on it when the inner drum spins, right? I think mine came loose when I managed to wrap the furling line around the drum. But that's like a chicken or egg. It's that a common occurrence?

[The Yacht Rigger]

Do you have any pictures of the top collar? There is a locknut up on the upper end of the drum too.
That lower portion definitely looks to have been "modified" - those two recesses in the bottom of the drum should have small lugs that engage on the lock washer.
I have a few old lower toggles with star washers and locknuts kicking around, and we've made a few replacement lower toggles - but first you need to get some lugs into those recesses so the star washer can engage on something.