[ROVERNET - UK] Alum/bonnet straightening

[Paul Smith]

If by "shrinking 
hammer" Paul means any of those with teeth, or swirls and cam 
mechanisms, I would say that the only legitimate use of such is to beat 
senseless the guy who sells them - they do evil damage to the metal.

Agree with comments about going gently and working it out as you said.
By shrinking hammer I meant one with a grid pattern on it, possibly "teeth" as you define.  For thin Al yes it would be too severe.  The shrink is only the Last step, to help fix the ding.
I have seen the Al shrink done so I know it works.

PVS