Main fuse blowing

Picked up a 77 KZ1000 LTD. Guy told my brother it ran great but as this beast gets off the truck from Iowa, it's pretty clear this isn't the case.   
Put new coil on because cylinder 1 wasn't firing and had carbs rebuilt (whole other story).  Changed jets, put them on the other day, got 3 kicks into this bike (starter not working) and I notice my neutral light is out.  Check the fuse and it's blown.   Figure might be age, had it running 2 hours ago no problem.   Put it another fuse, neutral light stays on 3 seconds then pops the fuse again.   
So now, I have a spade 20A fuse rigged in and the negative terminal off the battery and test light in series.   I have wiggled every frigging wire in this bike and I cannot get that test light to light up.  Removed headlight and everything.  My question is if I pull the plugs next to fuse box will that isolate circuits?   I disconnected the tail and polluted my test as the brake light starts blinking making the test light blink as well.     
I am going to put a spade fuse adapter in and see if that pops but if you have any other ideas, I'll take them.   

Can you please try and keep to one thread per problem, people trying to help you will get frustrated by two threads running n parallel. Where exactly have you connected the test light as it would normally be in “Parallel” not “series” ??