On my Solera, directly above the propane tank is the mechanism for opening/closing the slide by hand. On my unit, there is a 1/2 inch hex head nut (13mm is very close). And, it works..I tried turning it slightly and the slide moved. To sum it up, open the propane tank door and put your tool on the hex head nut and turn in the appropriate direction. My Solera is a 2011.
OTOH, the weather here in middle Georgia is very hot today...nearly 100 degrees. Glad we got a trip planned next week for the N. Georgia mtns.