Mickey, not sure what else you could do, mine acted the same as your describing, even while spraying them down I ran it up and down to make sure to get all/any hidden residue in the "nut" end as if they has any lube it wont hold.
Berj, your correct it wont lift the campers, however they wont hold any weight you place on them, they just unscrew until there is no weight...basically useless.
Good luck on finding a fix.
2013 F150 FX4 Crew Cab Lux Package
2013 Forest River XLR 27HFS