A few months ago I got my washing machine fixed. The problem was that
the drum wasn't spinning round although the machine was going through
full cycle (filling up with water, and emptying out with water at
appropriate times).

The repair man took out and replaced two small black blocks each about
one inch long and 1/2 " wide approx. I don't know what these are or
what they are called. He too them out form a large component in the
machine that is cylinder shaped approx 5" diameter and 6" long.

I'm sure these are quite easy to replace as it only took him about a
minute.

Can someone tell me what these two blocks are please and how I should
replace them?

The washing machine is a Hotpoint 95452

Thanks.