I guess the problem is in the fact that the pulleys can move, being attached to the wall with rope. Paul has good ideas on guides, so Ill leave his thoughts alone, but I might have an idea you can use.

Functionally:
Like Paul says you would like the to get the force comming from the water, so you will need an extra pair og pulleys, mounted close to the floor. Let the ropes enter here, go to a pair of pulleys at the ceiling and down to the weights. That would do something about the weights swinging. If you attach the pulleys to something solid, like boards, that would minimize your problems PADDLEWISE a lot.

Socially:
The wife needs to be happy! You cant afford a divorce with your work-situation in mind, so maybe use some leftover strip-pieces and make a closet-door like the ones in the room allready, mount it on the boardframe holding the mashine, and maybe that would help out you marriage lasting longer.

I know the mashine is El Cheapo, and everything adds up, but use the input if you can.

Gennie
www.byg-kajak.dk