44 swisher One of the cutting blades freely pivots and can be easily spun by hand, the other blade fixed and wont spin at all by hand. So should the blades freely pivot and spin or should they not move at all?

With the mower turned OFF check the blades to see if they aren't bent and if it spins freely. There should be resistance when you hand turn the blades. A bent blade can jam and lock up the drive system. If the blade spins freely and has no resistance check the drive belts from the blade pulley to the gears that run the blades. Hopefully you have just had a drive belt come loose or break, a reasonably cheap and easy fix. If the belts are OK you will need a mower mechanic to look at the gearing for the blades.

if by floppy do you mean that tips move up down 1/2 inch yes this is normal, if they move more ck spindle bearings ill bet your missing a few balls in there , and nope no belt should have chunks missing , and yes defective belts will slip and not get proper blade speed from engine to blades
clean out belt path after every use , that belt guide path is a magnet to sticks and stuff collecting there , also allways use kevlar belts , not ones from a car there not 4 to take the heat a kevlar belt will

The most likely cause is a bent blade. If the blades are not reasonably straight and balanced it will cause excessive vibration. I suggest addressing this asap. The excess vibration can cause more serious problems if not fixed.

Changing the belt on the swisher 44' rough cut - mine is a model RTB134412v. You have to remove the belt guard (4 bolts) and then the 6 bolts holding the engine on to the deck. Lift (or tilt) the engine up and loop the 1/2"x50" belt (I got a husky replacement belt at tractor supply) through the wire belt guides and around the engine belt drive. Then loop the belt around the larger blade drive. It takes about 30 mins or so. Hope that helps.

is the belt tension adjustment on the lever that engages the blades?

Remove the belt and try to spin the blade. If it still acts that way, you need to replace the arbor bearings. If it spins easily and smoothly and has no play side to side, then the motor is the problem.

I had the same problem twice. The first time happened when the blades were not swinging freely because they got gummed up with grass. So make sure your blades pivot easily.

The second time happened when the nuts came loose from the blade driver (the part underneath the deck that the large bolt goes through to hold on the blade assembly). I had taken the Swisher to a small engine repair place for servicing. They removed the blade assembly to sharpen the blades while it was there but put the old lock nuts back on without using any Locktight, so the nuts started to come off while I was cutting. Unfortunately, I did not notice this until after the blade driver got very loose and then got reamed out by the wobbling of the large blade assembly bolt. I had to replace the blade driver and its bolts and nuts.

The engine in this machine seems to be powerful. If you can remove the belt from the pulley that drives the blade. Try turning the pulley buy hand. If it turns tight or not at all this is your problem. The unit that is the pulley to blade assembly is seized or ready to seize. Sometimes they are designed to be taken apart and repaired, and sometimes they are not. Did you check for a grease fitting within the pulley to blade unit?
I would like to hear how this works out for you. Best of luck.

You may have worn blades that dont overlap anymore.

You should take your blades off and have them compared to new blades and see if they are a little shorter than they used to be.
If not....have them sharpened and put them back on. Check your Swishers belt tensioner to make sure the blades are all turning freely.

I dont believe there is a shear pin on your blade spindles, what I have found on these machines is the the spindle nuts on the balde spindles sometimes loosen or wear and no longer squeeze the pulley on the blade spindle. To make this process easy on your self you need to tighten these with a impact wrench. However if you dont have access to a impact wrench you can use hand tools and block the blades you are trying to tighten with a wooden block. Just make sure you block the blade you are trying to tighten