Burning highlights down to pure black. What's the secret?

Yes you are quite right. A terrible idea for this negative!

Id make a simple mask out of card stock, take the negative out of the enlarger while keeping the mask right above it moving it slightly and never stopping. it will make the two spots completely black.

Hey guys.

forgive me for the lack of input but I've not been terribly well lately and only went back to the darkroom this afternoon for a few hours.

So I've tried a few of the your suggestions, with mixed results...
I tried to darken those areas by applying hot water but that didn't do anything.

I also tried to add light to the highlights following a full development of the print. All I got was some grey or some solarization.

Fogging the highlights with a polystyrene cup held over the lens only resulted in greying down of those areas, following a 180 seconds fog.

The only thing that was a step in the right direction was the red light filter over the lens with the flashlight. However I had to make a little cone with a black card fitted at the end of the light in order to avoid fogging the whole print but even this did not give a very precise beam of light.

A dauxlite would really be the best thing. If anyone has one they could sell me please do get in touch.