I have a 24v Sky-tec starter for sale on Ebay that I temporarily (less than 10 starts) used on my TSIO 550. The link and more information can be found on:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180355364065&ssPageName=ADME:L:LCA:MOTORS:1123 

Thought I had a failing starter, but found out a it was a failing starter adapter.  If you have an Iskra starter, I would highly recommend removing it and putting a Sky-tec or Kelly Energizer on before you have problems like me and others on the list. 

Craig Gainza
Lancair IV-P