I think it needs to be more P-shaped whereas it's currently pear-shaped. The flat lengths should be parallel from the side view, beginning crisply at the point where the clamping (rounded) area ends on the shorter length.

I would go back to the vice with a 1/4" (?) spacer between the long length and end of the short length. Below the carriage bolt hole. Then place it with the vice gripping *just* below the point where the rounded area ends on the short side. You need to close that circle, with the flat lengths remaining straight and parallel. The piece might be too fatigued for this approach.

If it does work, you need a couple of thick washers with a nice tight ID and an OD that extends right up to the clamping area on the short length side, to keep that short length relatively straight.

[edit] You could leave a spacer wedged in below the carriage bolt to prevent useless compression/deformation of the non-clamping end of the short length.

Hope this all made sense.

I notice on my Ludwig rail arm that when you look at it on the side like your first photo, mine has serrated "teeth" on the edge; I wonder if there is a knurled area inside that L arm holder that meets up the the knurled edge of the L arm to "grab" it and hold the L arm in place when the L arm is slid in and the carriage bolt nut is tightened. If you look inside that area, does it look smoothed (perhaps worn away from use) or knurled?

My photo is blurry but it gives you an idea of what it looks like...

Does this make sense to you, V?

I think Mr. DownTownFarmer is on to something. Mine looks much like yours, but there is a subtle difference. Note the crease in the first photo. From the side, mine looks very much like yours but with a slight pinch-point as the bar is bent straight.

Josh

I’ve had the same issue with my hotdog rail or rail consolette L rod clamp.

I had put the carriage bolt back in with washer and nut to hold that position and manipulate the clamping surface to be smaller. (with hammer and dull chisel) It may hard to open back up to fit the L rod back in at that point. Be sure to try a little at a time. But once there, you’re good.

Otherwise you could try putting metal shim in the clamping area with the L rod.

A picture is worth a thousand words...which is about how many words I typed above :)

Mr. jmcohen introduced a key word - "crease". The crease must be crisp! Pic shows how these pieces are supposed to look when they're functioning. Red arrows highlight the crispness of the creases!

I think it may be a combination of the L-arm serrated teeth being worn down over the decades and metal fatigue of the clamp. I would try adding a thin piece of Aluminum tubing that would fit snug over the L-arm. It could be cut small enough to be hidden from view and add enough bite to secure the post firmly.

Additionally, are you sure all your parts are Ludwig? MIJ may not mix well.