Thank you all for your advice and help. That you are still helping me definitely says something about your patience, or my convincing skills, or both!
I have everything going okay now both with and without bones in both cases - the anim is totally identical so I think for my own comfort I will continue using bones where possible, I'm happier with them as odd as that may seem.
The only issue is that, even with it having frames at the start, middle and end, the piston rod still refuses to be included in the anim export. It's set up in exactly the same way as everything else - so why would this be? If we can fix this then we're laughing! Many thanks, gents.
