Baxi Solo boiler vibrations?

I had a Baxi Solo boiler installed 2 years ago. it started making loud noises which went on for about 1 minute before going.I had to record for the installer to return and sort out as he had not come across it before. He seemed to sort it out but a few weeks ago (just as we booked a service with a local man) it started making similar sound, but less noisy. It sounded like a power glider when heared from another room, the service man listened to the new recordings and when he serviced it he altered the sensor thinking it might be too high, or faulty. It stopped but has now started again. Any one else had this problem ?

Frustrated in Worcester
May 2009