Just an observation really.....

Fitted a replacement bonnet yesterday, mine had an annoying reverse dent from some clever person leaving a spanner on top of the rocker and slamming the bonnet earlier in it's life!

Anyway, the replacement bonnet had the sound deadening on (old one didn't) and the gas struts don't hold the bonnet as well as before. The only difference is the padding!

sounds like your gas struts are on the way out, only about a £10 off flea bay, i just had to change the ones on my boot

Just take the struts off your old bonnet and swap them