Short to ground. Please help!

Mymopar also has the Master Technicians series in pdf and the videos.
Howerver they don't have an index.
Imperial Club has an index.
https://www.web.imperialclub.info/Repair/Lit/Master/index.htm
There are a couple of pamphlets and videos explaning how the turn signals work and how to troubleshoot them and wiring in general. See for example 1965#2, 1968 #6 and 1967 #7