Some Alko hitches do groan, the principles of operation are similar to that of a disc brake.
First- do not use any cleaning agents or lubricants at all.
The pads are fine as long as they are smooth, free of chips and cracks (caused by clumsy hook ups' and not contaminated by someone hooking it onto a greasy towball. If they have been contaminated in any way with grease, they must be replaced.
Second- The towball must be the Alko 'long neck' type and be dry, smooth and clean.
cledlyn
June 2010