Well, Kennyd has a point, I too would start with a meter but I'm familiar with electronics troubleshooting.
For someone that isn't familiar with electronics troubleshooting, it's usually better to isolate the condition that causes the problem first, then start troubleshooting what might or might not be happening. That would mean potentially dozens of fuses or one breaker.
Personally, I think companies that make products like this skimp out and go the fuse route when they should ALL be thermal breakers with illumination. Sure, it's a $5 part vs. a $0.05 dollar part, but I'd rather pay the extra $4.95 when buying the $1000 implement than having to pay $20 later to install it myself. Anyone making implements reading this? Stop skimping out on the good low cost stuff!