Thank you all for the response. Some very good ideas. However I suspect that the problem might be in the antenna booster itself. This problem happened with the coach sitting in one place and it had been giving ok reception with a signal strength high of 55. Now just a signal that varies from 30 to 50 and the reception follows the signal, good to bad then back to good.
And it is constant, and does not change regardless of where the antenna is pointed. I should amend that, it does go up when it sees a stronger signal but the constant oscillation does not stop. Thanks again for all the great ideas.