Linhof 5x7 Bi-Kardan repair and/or CLA

[linhofbiker]

I have had this Linhof 5x7 Kardan Bi for some time and all the controls are smooth and precise with the exception of the part that slides on the rail and is secured with a clamp. When the clamp is released it is extremely hard to move the sliding part. I can see there is a wheel that moves along the groove in the rail. Does this need grease or is there something else that needs "lubricating"? The brass wheel rubs in the aluminum groove and should be self-lubricating. One odd thing about this camera is that every metal part is bright aluminum except for one of the rail clamps that is black.

[linhofbiker]

Problem mostly solved! I put a drop of gun oil on the wheel's surface and pushed the clamp along the rail several times, then cleaned the groove. Now the sliding is less difficult.