Richard Shaw

I acquired a second hand Coronado PST. The focus knob doesn't seem to have any effect on the image and, although it turns, it feels as if something inside the scope is "slipping". Is it worth opening up and taking a look to see the focus knob in action? Is there anywhere that services the PST without sending it outside the UK? Are there any nasty surprises if I open it up (springs, pressure points etc)?