We have a Barker Deluxe 3500 and when our switch went out we called Barker and they also sent out a new switch. I simply swapped it out and all was good, not sure why it has to be synchronized as the limit switches are internal and decide when the jack has been raised or lowered to the max positions.
Their
website has owners manual which makes no mention of synchronizing any switches. We love our Barker, it has dutifully raised our very heavy TT TH and crew cab Silverado 2500HD that has a bed full of firewood, 3.1K watt generator, and other miscellaneous camping gear for over a decade.