Aye, chicken sticking to the skewers is a problem. I've largely overcome the issue by wiping down my skewers with kitchen towel soaked in a little vegetable oil before I thread the chicken on. Generally works fine for me, although I use a charcoal BBQ to do my tikka etc nowadays so it might not work with more direct heat.
EDIT: Just re-read your piece, Mick, and realised that my solution would just exacerbate your problem! Still, it works well for horizontal cooking!
