Topaz - leaking high top window

One of the ("Para press") side windows in the high top is showing definite signs of leaking.

My intention is to remove the complete window and re-seal the frame to the roof with Sikaflex 512.
My issue is that, having removed the interior trim, and then all the fixings (the latter curved sections of aluminium extrusion with a screw in each), the window frame shows no sign of coming loose.
Has anyone any tips on how to remove the window without damaging the window frame or the roof ?
I get the impression that these high level windows are notorious for leaks (between the window frame and the roof), so I'm sure others must have gone through this.

I presume yours must be similar to mine.
After removing all the fixings etc I had to prize the frame from the hi-top. 
It was held in place with mastic strip.
I used a Stanley knife to cut between the frame and hi-top.......very carefully!
After a bit of prizing, eventually it came out.

The worst job was cleaning up the mastic tape that was left behind.

Didn't bother with all those silly ally brackets, just bonded it back with CT1.
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I did use clamps to hold in place for 24 hours.
This sort of thing:
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Had to open the window for this to happen.

The hi-top had slightly distorted over the years, so needed the clamps to ensure a perfect seal.

Sealed over 12 months ago and perfect!

PB

I found exactly the same thing, but if you keep pressing all round you will eventually find that one corner gives and then you can work it out from there. IIRC I used a wide bladed screwdriver to get between the frame and the roof, but obviously you can only use a very limited amount of pressure or you will damage the frame.

Unlike PB, I used a more recent version of the mastic strip (as recommended by A-S and supplied by them), not adhesive sealant. If you use mastic then you should re-use the alloy brackets, as they are used in the process of "squeezing" the mastic out over a period of several hours. The procedure recommended to me by A-S was to install, tighten down steadily and then when the mastic has ceased to be squeezed out any more, run a blunt knife round the outside to cut off the excess mastic and then run a bead of clear silicone sealant around the outside to finish.

Thanks Peugeotboxer and Mojo for your advice.

After much levering with screwdrivers and hacking away at the mastic with a sharp blade, I eventually got the window out. Hurrah!

I've temporarily put it back in, and I'll make a proper job of sealing it at the weekend (if it's not raining).

Cheers.