Electrical issue with my mini lathe

[Monostre]

Do you have any kind of link to the "simple potentiometer" article? It sounds like just what I'm looking for. Thanks!

I linked it in my previous post

 

[Houthans]

The motor cost me €140 and here are some photos of the setup

 

[Houthans]

I'm happy using it as it is, but I may change to a pot meter some day. At least I have a working lathe again. Many thanks for all the help!