We had a problem with our Thompson machine on our year 2001 SM331. If you have the same model as ours, what we found was:
To free the drum on the washing machine, you open the lid and you will see a grill on the side of the machine towards the bow. Take this grill off and you will probably find it is filled with sediment. This you can remove by chipping out with a screwdriver. Next you spray the bearing / seal inside with WD-40 from inside the drum. After WD-40 treatment, you free the drum by carefully rocking of the drum back and forth. You can do all of this without dismantling the machine - as we did of course!