PBM Aprilia's James Ellison was forced to retire from the second MotoGP race in a row at Estoril yesterday as the front chatter problems he thought had been solves with the new softer-construction Bridgestone returned with a vengeance.

The Kendal man had been able to run with the fastest CRT men at the beginning of the encounter but as the tyres wore, chatter came back which made his machine unrideable and he rolled down pitlane.

"Pulling in again was a very, very difficult decision for me as the team worked so hard all weekend to cure the front chatter which is like a very heavy vibration. We were making some progress by the time we got to qualifying and had a good plan in place for the race to reduce the problem," said Ellison.

"The start was good and I was fighting at the front of the CRTs like in Jerez for the first few laps but as the tyres wore the chatter got to the point that it became unpredictable and in some of the fast corners it was pushing me a couple of metres off line. At this point I was only able to ride around and not actually race because it was getting worse.

"We are working hard on trying to find the source of the problem and I believe that when we do we'll be back at the sharp end of the CRTs. I'd just like to say a huge thank you to Paul Bird and the whole PBM UK team for their hard work and patience in what is proving to be a difficult start to the season."