Hey there, been through a few of those blue rubber seals recently myself, although i must admit my problem was self inflicted, i was using a true blind filter. So for me the pressure was way into the red for 4-5 seconds at a time.
From your description it doesnt sound like the pressure is building up too much. But if you are running the pressure into the red zone of the gauge frequently then that could be your problem.
other reasons could be:
- something sharp is resting against the seal.
- 1 of (or possibly both) the shower screens arent the correct screens.
- basket isnt sitting right (but i doubt this)
Can you give us any other background info? Did you purchase the machine 2nd hand? Can you take some photos of the area that the seal sits as well as the shower screens. Any other info that you could think of could help diagnose the problem. Also what area are you in, there might be someone local that can have a quick look for you.