i had the same problem "Incoming Packet was garbled on decryption".
for the connection i used:
> putty.exe -proxycmd "plink.exe john@81.163.163.63 -P 22 -nc 10.10.10.10:22 -i c:\Users\john\.ssh\id.ppk " john@10.10.10.10 -i c:\Users\john\.ssh\john.ppk
the solution=> First of all launch "plink" part of the command:
> plink.exe john@81.163.163.63 -P 22 -nc 10.10.10.10:22 -i c:\Users\john\.ssh\id.ppk
it will ask "the server host key is not cached". Just click "yes", "yes" etc.
After that launch full command:
>putty.exe -proxycmd "plink.exe john@81.163.163.63 -P 22 -nc 10.10.10.10:22 -i c:\Users\john\.ssh\id.ppk " john@10.10.10.10 -i c:\Users\john\.ssh\john.ppk
in my case it solved the problem.