It sounds like the closing arms need to be lubricated. They get dirty after a while and cause restriction between the arms and the spring clips. The best way is to remove the s/r, lay it flat w/actuators up and clean all the spring clips & sliding surfaces. Then lube w/a light oil such as 3in1. Graphite is much too messy for this and silicone is too thin. Remember, this stuff hangs upside down. As long as the s/r is out, clean & lube the entire actuator the same way. Then clean the feet and sliding rails, and lube the rails w/silicone spray. Once everythng is clean, you may have to readjust the closing arms if you are able to move the s/r from a locked open position, so check it at various positions.

__________________

Don't Chrome them; polish them