Two apologies:
- One for not reading the Reporting Problems instructions completely (and
missing cygcheck.out request)
- One for not seeing the helpful emails from Ken Brown and Marco Atzeri
Sorry!

Updates:
-Attaching cygcheck.out.
-'cygcheck /usr/bin/convert.exe' also runs to completion without reporting
any errors.
-'/usr/bin/' precedes any system directories in PATH.
- reinstalled libgs9, libMagickCore
- updated Cygwin DLL to 2.2.1
- problem still persisting:

~ $ uname -a; convert --help
CYGWIN_NT-6.1 IPAK-jpfeiffer 2.2.1(0.289/5/3) 2015-08-20 11:42 x86_64
Cygwin

Many thanks!
Katriel