This applies to manual awnings only.
Usually this is because the awning material has moved in the retaining slots. Now instead of being square with the main awning rail it is moved forward/backwards in the rail.
When installed the installer is supposed to add a retaining screw into each end of the rail, through the fabric to hold it in place.
Sometimes this is caused by the awning material stretching/shrinking oddly; then the screws must be removed, material realigned, screws reinstalled.
A temporary remedy is to re- extend the awning if the arms do not mesh properly. The push the end of the awning tube toward the same direction the rails are not meshed, kinda like attempting to rock the awning to make the material slide in the rail.
2000 Winnebago Ultimate Freedom USQ40JD,
ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy