Hi wasn’t sure where to put this, but I have recently had a similar problem. I stuffed one of the metal covers.
Apparently can not buy as a parts, I find this a little odd.
Any way looked at options and made my own.
Used clear plastic laminating sheets, place two together inside each other and laminated in normal machine. The two gives a total of 4 thicknesses and add strength.
cut to 5/8 wide and longer than the metal strips by about 50mm. Punched holes to suit clamps and installed in usual way.
left the ends long so can pull to tension rather than using that clamp device supplied.
Works extremely well at an extremely low cost and has removed a rather loud noise from the rail when in motion.
You must also not tension the steel band too much, otherwise it comes to damage the surface, I have seen with a user who sent me a picture !!!
Here is the picture if you pull the steel band too tight!!!
Ah, ok. that’s akward. It was part of the older “A” models by default. On the other hand, it was also the tool that at the time everybody on the forum was asking about because nobody knew what it was for