It sounds like you will need a court order, which can be fairly easily obtained:
§ 3137. Enforcing production of will.
The register, at the request of any party in interest, shall
issue a citation directed to any person alleged to have
possession or control of a will of a decedent requiring him to
show cause why it should not be deposited with him. In the
absence of good cause shown, the register shall order the will
to be deposited with him.
You can get a free consultation from some of the local probate attorneys listed here.
You should be able to file a probate petition asking for appointment as Executor even before you have the original Will.
Please follow up on this with a local attorney.
I hope this information is helpful.