Pulpit guard rail repair

[StefanSG]

I needed to cut into my pulpit guard rail to allow access for navigation light wiring, (yes too late now) there is a hollow joining tube made of aluminium that joins the sections together, it has corroded to the point that it has swollen the existing stainless guard rail. Any tips on how to rejoin, and how to remove the corroded sections either side of the joint.

thanks

StefanSG