I think this trick works well on the glass windows that push directly out (hinged at the top) from the bottom. The 1991 345 motorhome I saw last week had slider windows in tracks. Not sure this method could work, but one can try.
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TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels