Bit the bullet and replaced our Solar Vents - Marinco Nicro 4" Vent & Fan.
Looks to be a much better product than the original broken units (head & aft berth) but, at nealy $180 (pick up at store when we needed them) the pair cost more than a home Microwave cooker!
See blog for details: http://www.sailingeximius.com/2016/10/time-to-vent.html (http://www.sailingeximius.com/2016/10/time-to-vent.html)
Paul
Good luck. Not to be a naysayer, but I replaced mine with the "new" replacement and hasn't worked almost since the day I installed it. Albeit it is blocked by the dodger some of the day (ok, maybe more) but so was the old one and it worked for years. Lots of info on the web about "Nicro doesn't make them them the way used to..."
Edit: I have had very good luck with my small Eva-dry 2200 dehumidifier (recommended by Practical Sailor). I keep plugged into to shore power, so it may not be for eveyone. I also did the modification they did--drilling and installing a plastic barb fitting into the removable water reservoir with some small PVC tubing, so I don't need to empty water. Unit sits on galley counter and drains water into the sink. I can keep it running 24/7 at the dock. Keeps boat dry and fresh... Works in CA but maybe not SoFL. I can also leave my head hatch cracked open as it is under the dodger. That helps, too.
During prep for H Mathew, I was at the boat today, turned on the two solar vents and they worked beautifully even though they are under our dodger too.
Paul
Congrats! Better luck than me...
Replaced mine at the end of last year with Marinco. Works perfect. WM had then on sale for 50% off! Watch for the sales!