Adrian,
Thank you for the insight. I have the same problem with several 7A29s. They worked fine years ago, but now all except for one and a 7A29P have the issue you describe. I thought it might be the attenuator resistors deteriorating with age but maybe it is just the ground contact that you describe.
It was hard to account for the deterioration in rise-time from misuse or static discharge as they have spent most of their life stored in the scope cart drawer. I will investigate and report back. George
