Originally Posted by Karlos G

Yes, and if you changed actuator... yes!

Amal valve pipes go:

C=Compressor Housing
W=Wastegate Actuator
R=Return to metering Unit

These letters are marked on the Amal itself but you might need to take it off to see them.

Try winding actuator rod out 2 turns at at time until boost increases.
If you are using the same actuator as before and have not altered the rod length then leave it alone, it's probably something else!!