*Slaps forehead*

Thank you for your time. Tipping GnuPG and marking issue resolved.

https://projects.archlinux.org/svntogit/packages.git/log/trunk?h=packages/gnupg
looking through the commits there I can't see anything that pops out as related.
The change that affects me wouldn't have come before 2015-07-01
My C is not very good and I haven't looked through GnuPG source code but the
commits since then don't seem related to importing keys.

Decrypting works successfully, I should have specified earlier. Here is output-
log2.txt
I am also attaching sec , the decrypted sec.asc in case you are not able to
import (my) sec on your system

According to this
https://wiki.archlinux.org/index.php/Arch_Linux#Simplicity
it is unlikely that the Arch Linux devs applied any patches at all.

Thanks,

Here is sec.asc

Ok, so after further exploration, the error is related to the way I am encrypting
the exported secret key blocks. I Do NOT get this error importing private keys
made wit
h gpg -a --export-secret-keys. However, if I symmetrically encrypt the secret key
file, I get the 'merging secret key blocks... ' error. I did this in output-
log.txt whi
ch is attached.

This leaves me with 2 questions:
How should I encrypt my secret keys after I export them in a way that doesn't
break things?
Is there a way to get back my secret key that was encrypted earlier and gives me
this error??

I am also attaching sec.asc
the symmetric password is 'password', as well as the password protecting the
private keys.

My operating system is Arch Linux. There was no configuration file (I cleared
~/.gnupg before the session in output-log.txt).

Gniibe, thanks so much for responding btw. Ok, there is a new update:
I made a new keypair for personal encryption while my current one is being sorted
out, and the EXACT same error happened when I tested my backup of it. There is
either user error on my part in the --export or --import commands, or a bug in
the way GnuPG imports or exports keys.
Therefore, I want to replicate the issue with an example@example.com key for you.
Before I do so, is there a preferred way for me to log the session so I can send
it to you along with the public and private keys?

Ok, here is the stderr of gpg -ivv sec.
This is into a clean ~/.gnupg on my regular computer. Is there a debug level you
want me to specify?