Checked archieves and didn't find anything that would help for the 340 type rigging, so . . . Periodically I feel the mast on my 7 year old 340 shudder while at the dock. Typical it is with a 15 - 20 mph wind abeam. The problem seems to have grown over the years. Last year I tuned the rig with Loos gauges and their recommended tension. The shudder seemed to lessen or disappear. However this summer it has returned. The mast bend appears about the same and within the limits provided in "the book". However I will be doing a careful check of that, too when I go aloft. Winters In South Dakota chill to 10 to 20 below and summers to 110F. I would not have thought that such temperature variations would have caused the problem, but maybe I am wrong. So, I plan to climb the pole again and check the diamonds to see if the tension has changed. However, before I do that, I would appreciate any thoughts anyone has on what else I should be checking. Thanks. Jim