you r using the incorrect strap for the mk2 RES2. you need the LT strap , that secures through the handle at the back , on the top or the RES2. look at funktion one rigging info. you r gonna drop a speaker perhaps, cause teh handel is larger on this cabinet than the previous one. who knows what damage may occur of a 55 kilo cabinet falls... check it out..
u guys make 55 kilos look heavy. why twist the cab on the way down, why not lift straight up , both take a step away from bass cab, and drop the res one straight down , onto its bass. much easier an less stress on your bodies when you twist the speaker. Working with someone that is the same height as you , (tall) , makes lifting an taking down, much easier as heights r more balanced. less stress on both people..