Crickey that hood is in poor shape, wondering if it has been subjected to trauma rather than natural stress fissures?
I own one of these, in Vista Blue and one in black, I also have spare NOS barrels for each pen. Of my two Special Editions and the spare barrels, there are no cracks at all.
Given the level of damage to that hood I would source a replacement, that pen is certainly of value to warrant the expense.
Otherwise I suspect the results, whilst possibly stable, will be obviously 'repaired'.
Your best best is a mix of superglue and fine sanded dust from a older cracked vista blue barrel if you can source one.
I know, from the luthier repair industry there is a plethora of different superglues available. It may be worth researching the glue and sourcing damaged Vista blue plastics for the filler dust.
Edited by jaytaylor, 13 August 2019 - 10:39.