92' xl 40' converted

[bobrl]

Afternoon all!  My Coach is a 94' Conversion by Monaco, Royale. Working on the level low system. All works great except every once in a while the left side wont operate up or down, seems like if i rap on the five valve body it then works fine!!  Is this a sticky slide in body or what ya think?  Can i lube the slide in body, or am i way off??? Thanks for any help please!! Bob in Il!!