[Shop-talk] What lube for this application?

[cornerexit]

I just installed this lat pull-down attachment on my sons weight lifting
power rack. The main tube is square steel tube, chrome plated, and you can
see the plastic insert in the black slider tube of the carriage. There is
one plastic insert in the top of that slider tube and one in the bottom.
This design does not slide anywhere close to smoothly. We have to stack
quite a bit of weight on the unit to get it to work at all. All the related
pulleys, cables etc move freely. The binding is in the interface between the
plastic inserts and the chrome plated main tube. 

 

What kind of lube can I use on that chrome plated main tube to help this
situation? I hate to use any sort of oil based lube for fear of what effect
it will have on that cheap plastic insert? Maybe some auto polish or some
chrome polish??? Is there some sort of dry lube that work in this
application? Bar of soap?

 

I have a feeling I'll need to change this design eventually as there is very
little surface area in the plastic inserts riding on the main tube. Wonder
if I could pull those two inserts and glue a four very thin strips of UHMW
to the inside walls of the carriage tube?

 

http://waynef.smugmug.com/photos/176378982-M.jpg

 

Thanks

Wayne