Sounds like “maybe” you should be replacing both your coach batteries (assuming they or your charge system are damaged) and I would highly suggest that when you do that, you also should check your battery charger (converter) and charging system with a multimeter to make sure that it is actually working to properly charge your new batteries. No sense buying new batteries only to have them sulphate to an early death from a poor or non-working charging system. I can’t recommend what to buy because everyone has an opinion about this topic. I personally will always use lead acid wet cell batteries (cheap and reliable if looked after), because I monitor my charging system regularly and seasonally check water levels in the batteries. I am a seasonal camper so this works for me. I don’t know what group size batteries your coach takes, but you can measure them and compare dimensions to the table attached, which should help zero in on the group size that will fit your battery compartment.
I am not a 5th wheel landing gear expert by any stretch, but a broken pin anywhere on that apparatus sounds like a serious safety problem waiting to happen. Replace/repair it. Also low battery voltage will most certainly cause motor problems for you by increasing current through the motor windings and will probably reduce the life of your motor. You may find that with fully recharged batteries the motor behaves like it should again if gears are OK. I would personally inspect the landing gear and lubricate lead screws and gearing as required, assuming all the gears are still in good condition. If not repair them and make sure they are properly lubricated. Safe camping.
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