I disagree, WD 40 is not a lubricant primarily, it is a water-displacing formula. It becomes sticky when it dries and just gums up moving parts.Been there, done that.
Sometimes the gearbox must be replaced, sometimes the linkage is binding and must be corrected. The gearbox is lubricated with a heavy white grease, which can become hard over the years. A drop of 3in1 oil on each moving joint is recommended by the mfgr. if it needs lubricated. I have replaced gearboxes and straightened linkage on some of our old trailers. It is not difficult, and replacement parts are readily available online. It is easiest to remove the entire window to replace the gearbox and work on the linkage.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"