Laser cutter power issue

Hi everyone,
I recently installed a new tube and power supply to my ls3020 laser cutter. Everything has been working fine for a few weeks (machine has done approx 30 hours of cutting/ engraving) however, I went to the machine today and have massively reduced power from the tube and it will not cut through 3 mm mdf.
I ran a testjob and looked at the laser whilst it was cutting and I am getting a strongish purple glow from both ends of the tube but nothing in the middle. However, when I press the pulse laser button I managed to get a very strong full beam throughout the tube.
Any ideas why I'm not getting the correct power when I'm trying to cut an actual job?

It sounds like a possible power supply issue unless there is a loose connection. Sounds to me like a capacitor breaking down in the supply, it can produce a short pulse at nominal power but not sustained nominal power.

Someone else might be able to confirm my thoughts.

I think makercut is right. You should check your power supply issue.
Do you have a user manual?