Kurt Ullman wrote:
Thanks for the reply. I think the diagnosis will take more time than
replacement, and the string is low enough on the tree that it will only
a minor pain to change it out.

A string of 25 8 watt bulbs would draw less than 2 amps. Two strings
in series would not blow out that 5 amp fuse. Clearly there must be a
short in that string. Load would approach excessive if three strings
were connected through that same 5 amp fuse.