The executor has a statutory duty to allow inspection of a will by eligible persons.*
At common law, this has to be reasonably promptly.
If necessary and if eligible, your son (even if a child) can apply for an order requiring the executor to allow inspection.
The beneficiary will get the best result if they engage a solicitor to assist them
with this kind of application.**
Who the the solicitor is less important, first up.
Once the Executor is served in person with the a copy of the application,
it will quickly become apparent who his lawyer is.
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* s50 Wills Act 2007 (Vic)
** in certain circumstances, the costs of things liek this can be paid by the estate.
Discuss this with the solicitor at your first meeting.