If you just want to check it works, put the red and yellow in a bit of insulating block together and the light should come on.
The trouble with a lot of dimmers is that they sometimes die if a lamp blows.
You could try the main dimmer (red to L and yellow to squiggly). It may be OK.
PS Make sure there the front plate is connected to earth, if you are using metal plate switches. I looks like the old ones weren't
The trouble with a lot of dimmers is that they sometimes die if a lamp blows.
You could try the main dimmer (red to L and yellow to squiggly). It may be OK.
PS Make sure there the front plate is connected to earth, if you are using metal plate switches. I looks like the old ones weren't