Well I didn't expect that! A reply from JSTOR arrived in the time that I was typing my message on this list! Although the solution is a tiny bit fiddly, the result is very acceptible.

This is what they told me:
Dear Giles,

Thank you very much for your message. We are always happy to provide you with screenreader-compatible copies of articles upon request and free of charge. You can email us at support@... or use the prompt that you hear on the article page to send us an automated request.

Alternately if you run out of JPASS downloads quickly as you download articles that do not feel relevant, we will replenish your downloads at no additional cost to you.

The article you requested today is attached to this message as a high-quality PDF. It is saved as the following file: 26779641.pdf

If you have any further questions, please feel free to get back in touch!

Kind regards,
EJ

* And I have downloaded the PDF file they attached and it is ordinary text, not a scan that needs running through OCR.

Giles