I just got this e-mail from Hekman and it wasn't much help. You guys had already told me pretty much what they told me too, but at least they did return my e-mail.
Desk was called a Spinet Desk, Hekman manufactured several styles in the late 1920's early 1930's. Based on the Hekman name stamp (photo) you provided can confirm desk was manufactured during that time. Desks were of Mahogany and Gum or Walnut and Gum. Due to limited incomplete catalog history this is the only information we can provide. Would have retailed for around $50.00 at that time you would need to check with an Antique Appraiser for current value