New Grub2 verses Debian 9.5

[jmh6]

Hi All,

   Finally I can almost understand what Grub is trying to do. Good job 
making Grub less opaque :) :). Thanks to all.

   I normally run with an SD card plugged into a USB2 adapter. Neat. I can 
change OSs in a blink and easily keep my user files on a plug in hard 
drive :). Nice.

   When I installed Debian 9.4. It just worked. 9.4 had some other 
problems though.

   I have spent quite a bit of time trying to upgrade to Debian 9.5. While 
Debian 9.5 allows me to try to install to an SD card, grub will apparently 
NOT do the necessary work!!

   Right now I can boot Debian 9.5 on SD only by using the grub recovery 
memory stick to start it. The recovery memory stick DOES find both the SD 
OS and the 'main' hard drive and allows me to start either.

   So far I have not been able to figure out how to tell grub-install to 
put in the correct start address, etc. Grub-install fails with some 
obscure message saying basically I will not do what you want. This is 
apparently a new 'feature'.

   I even tried copying the first 512 bytes to the new SD to see if that 
would 'solve' my problem.

   Now, I can see the low level grub boot jumping to some wrong address 
and giving screen patterns, but no boot.

   Suggestions please on the necessary magic sauce to get grub to do 
whatever deed it needs to do.

   Thanks in advance for your time and help.

   Lots of fun :).

   John