Aluminium Windscreen Surround

[laika]

Laika's windscreen has been completely UV crazed since purchase and polishing hasn't made it see through so I want to replace it as part of the refit. To do that I need to remove the plastic from the surround to give it to the local plastic people to make me another. Fortunately a previous owner's use of duralac and plastic washers made the screws attaching it to the bottom part of the aluminium surround relatively easy to remove, but I'm stumped as to how to address the top part of the surround (apologies for the curious blue hue)
View attachment 31096
The top part of the surround is (now it's removed from the lower part) attached to nothing but the plastic: no screws anywhere. There doesn't seem to be room to get a razor blade between the plastic and the aluminium. Wiggling and moderate force have had no effect and before I attempt force that will damage the aluminium I was wondering if anyone has dealt with this before and what approach would be recommended.

Additionally...what top tips do people have for restoring mildly pitted and corroded aluminium?

 

[TradewindSailor]

I haven't seen this before, but my guess is that it's pressed on.

You may not get the aluminium section off without damage though. I would try using a block of wood against the edge of the frame and tap that with a hammer .... little by little, a working it along the edge.

Good luck.

 

[laika]

I haven't seen this before, but my guess is that it's pressed on.

That was my thought. If that's the case the question would probably be how I would think about getting the thing back on again when I have the new plastic, or am I into the territory of having to get a new frame made?

 

[Neil_Y]

I have never tried this, but as the plastic will soften with heat it should then be possible to stretch it by pulling it away from the frame, it will then get thinner and come out? That's what I would try.

Hg kitchen steel polish is good for restoring Al, for a polished finish then use Solvol autosol.

 

[dingdongs]

if you could make some sort of wooden stepped fingers up which would fit either side of the aluminium and bolted together so they would slide under the frame.This could be eased apart with some light tapping.Some sort of silicon and some clever sort of clamping could reassemble it afterwards so its secure and watertight.The oxidising may be best to either address b4, so it does not mess the new screen but differing emery grades /wet and dry and some autosol may be the best way to go b4 reassembling.