Hi Norm,
Firstly thanks for the response.
As far as Bushing goes I had thought of that previously and just haven't gone any further with it. I thought of inserting brass tubular bushes into a drilled out hole of the corresponding size and then I thought of turning up some industrial grade nylon and inserting that, but these are just ideas atm and as such it seems like you've done this before. 
How would you envisage doing this particular job ?
Cheers,
BB.