I never had to deal with retail patching of mowas as I always used the game on steam but there are few suggestions:
1. FIRST make sure your original version has no extra files anywhere under root folder where binary is or under resource folder. If you not sure delete entire folder after you uninstall the game. Make sure nothing is left over. Then reinstall the game.
2. Once you have the game installed as original version, grab
http://www.1cfiles.com/MoWAS_patch/m...05.13-full.zip assuming your game is not GOTY there are other files for GOTY. Install this patch.
3. Next get
http://www.1cfiles.com/MoWAS_patch/m...-small.exe.zip and install.
4. Finally get
http://www.1cfiles.com/MoWAS_patch/m...-small.exe.zip and install.
If you still have issues then its possible 1c made mistake doing the patches, but please make sure you have either regular retail version of mowas or goty and not some other type of special version or custom store download version(I heard about some weird versions).
Another trick is to use steam and register cd key with steam BUT keep your original install of the game in another place that you installed non steam version. Once steam patches new installation(under steam folders usually) and you know that is all patched properly you can copy over all the files except for the exe I believe as that would have steam drm I think, so the key is here whether you can get new exe for retail off the 1c patches. However, this way you could test whether the steam install would work fine, then compare all the files steam installed vs the ones patched with retail patch on retail install and find out the problem. gl.