The problem with my very old washer was that the tension spring had broken long ago and I had jerry-rigged it in place with a cable tie. It would work, but you had to give the drum a spin by hand when it hit the spin the cycle. This probelm further caused the premature wearing of the drive belt, due to slippage. I ordered both a new spring and a new belt. Upon their arrival, I removed the two screws holding the front panel and lowered it off and out of the way. The old, worn belt was very easy to remove, as there was very little tension on it. Next I attempted to remove the washer that holds the idle arm on. It is in a very awkward spot, and it appears the the washing machine is sort of built around it. I bent it gradually with locking pliers until I could force it off with the blade of a flat screwdriver. Then the idler arm was easy to lower of its axle by twisting the drum a bit and pulling it to one side. I put the new spring into the idler arm, making sure the plastic bushing was in place and replaced the arm. I then repositioned to belt and replaced the front panel. It works great now.

removed the front of the washer
removed the "C" clip holding the idler pulley assembly in place.
replaced the broken idler pulley tension spring.
reassembled the idler pulley assembly.
installed a new "V" belt just for good measure (it is after all a 15 yr old washer....)

the hardest part was getting the "C" clip off and back on - but that still took less than 10 min total...

Tensioner (pulley spring) replacement.

The whole tub and motor are suspended by springs so I just got a flat bar and using the edge of the bottom of the washer as a fulcrum, lifted the whole thing enough to be able to shove a 2x4 under there at the base of the dome. It was still tight getting the lock washer off the bottom of the spring axel, but it popped off by pushing the ends with two screwdrivers.