Memory says much of the tail rotor vibs came from the blade extension arms not having the same amount of 'Grease' in them, the wieght difference causing the vibration.
First IA on recieving reports of TR vibs was to purge all four extension arms and normally this would cure the vib.
"The vibrations and subsequent cracks came due to an lack of knowledge from the maintenance team. When they got the knowledge, the phenomenon went away."
Please believe me it was a painful process
The early 80's where the days of the 3 Sqn Regiment, newly set up and down to be the rapid anti tank attack force if Ivan came.
The bare faced lies that where told by the engineering side to Make aircraft 'S' would even embarrass me.
We found that when doing MR vib check that if pilot placed aircraft in a very shallow dive, then head vibs where much lower and the cab would pass the test.
Not honest but until late 80's no one had the solution to the dreaded 4 R vib, that Lynx developed after say 300 flying hrs.
The lies and Sh1t told to get around that one, from both Engineering and Flying side where legendary as any honest person involved at first line can tell.
john