No power?!

Help! Out of nowhere I am getting NO power to my bike (1979 Honda CM185). I'm not electronically or mechanically inclined, but I've learned a lot over the last few years with the bike, so bare with me. It happened yesterday after work, I was able to run and jump start it once, was able to get it home. Tried for a half hour again today but can't get it going again. Completely dead.

I have tested the battery... it is good and holding a charge no problem. Checked the fuse, it was blown (cap fell right off), so figured that was it and replaced it... Well, actually, I couldn't find a 20A fuse that fit in the original fuse holder since I have a 6 volt system, so I wired in a new fuse holder and am using a 20A fuse rated for up to 32 volts.

Anyways, replaced the fuse and reconnected the battery, STILL NOTHING. So I'm wondering where to look next. Ignition switch? Is that a big job or fairly easy? My dad is coming into the city this weekend and has electrical knowledge and will probably bring a current tester so we can check where the issue is. Am I on the right track? Or could it be something more complicated?

Thanks!