It's just heavier.  Most jacks have a little play that could possible be why yours appears bent but still cranks ok. If it is truly bent, You would feel the resistance as the jack gets almost totally cranked up and the piston portion of the jack started to bind

Have you oiled or greased it?

On the top sides of the gearbox are some grease fittings. If they haven't been utilised in a while, you might  grease the internal bearings. The top cap is removeable and allows access to the gear box. Digging out the old grease and applying new will lessen the cranking effort. Below that is a gimble nut and jack screw. Sometimes a spray oil applied with a small tube applicator can hit and lubricate those moving parts.

The gearbox shifts between ranges by pulling or pushing on the crank handle. If the gears are binding, the high range gearing may be stuck and the reason for the difficult cranking. On our trailer we use the low range gearing for raising the trailer, the high range to lower it. With weight off the jack, using the spray lubricant and grease, coating all the internals and fully working the mechanisms, should return them to their original condition. If the lower leg retracts fully without binding, it should pose no problem with the jack's opperation.

The easiest way to service a manual jack, is when the trailer is supported on its pin by your towing vehicle. With the weight totally removed, the jack is free to move without any weight encumbrances. With an adapter, many jacks can then be raised and lowered using a modest electric drill, which easily allows the jack to be quickly run from limit to limit with little effort.