being it an '06 model, are 'we' the dealer?

So you only watched the drives while it was on the trailer and could see it shaking? Have you unhooked the steering rams at the drives and then trouble shoot? Might be best to decide if it is a mechanical or hyd issue. Only at idle speeds. No problems when cruising?

It's a 06 34 kachina.. Who really knows.. but kachina.. says it copied a 35 fountain mold.. minus the bill in front.. from a wrecked boat... did not disconet the drives from each other.. but will try.. I have the boat at quailty marine in corona.. rob is a autorized mercury racing dealer and boat repair.. very bright person.. but is scratching his head...

yes only at idle... with drives up at 6... all goes away... remember... if you take the sterring wheel and go right to left quickly.. serval times... it also goes away.. leading to belive there is air.. but trust me... everthing has been double check 3 times... every fiting... re-sealed... talked to imco.. 2 new helms...

Does it happen also while on the trailer?

Scratching my head too! Good Luck

Never heard of the coping a 35 Fountain story, but if so, you got a great hull design.