These days it would probably cost less to buy a decent used handheld light meter than to fix an old built-in meter on a camera like the Pen. For years I've used a Gossen Luna Pro with 'spot' attachment.
For anyone else interested in a light meter for an old camera, my coworker's friend developed a small light meter and spot meter that are pretty interesting (and affordable): https://www.reveni-labs.com/
