Oh. I had a look on a spare 550 I have, as the 'working' one currently has a tank full of fuel and I couldn't see an easy way and so what you've said Norm sounds about right. Looks like a PITA and I suspect that knowing my luck I'll either break something or when I open it there'll be loads of grease and so nothing to do. Hmmm I think I mighht pass on it for now as looks risk vs reward trade off a dud deal for me. Much thanks for the feedback and advice.
