Well, with all the falderall try this. find a 6.3vac core with an output current that is adaquate. By examination, determine the turns/Volt for the secondary. method B: wind 5 turns over the core and see what the votage is. divide by 5 to get turns/volt. Divide that number into 1.7, that the additional voltage you need. Add those turns. That was the exact method used to correct the early version Altair with the undersized transformer. FYI, it needed 11 more turns of #16 to do the trick. No need to disassemble or "rewind". Allison