Hi Andy,
your camera is a re-badged Mamiya 4B, they came in quite a few flavours, early versions made entirely in Japan, later ones with Japanese lens & Korean body. Some of the later ones had a cds light meter, instead of the selenium one fitted originally. In general, those intended for the British market had a Mamiya Sekor lens, those for the USA a Mamiya Kominar, either version being f2.8/40mm in a Seikosha shutter, 1/4sec-1/250+B.
To adjust the vertical alignment of the rangefinder, remove the two screws holding the accessory shoe and remove it, revealing a hole in the top cover 2.5mm dia. Beneath this hole is a slot headed screw, which is central in a wedge device; insert an appropriate sized screwdriver, engage the slot, and turn gently whilst looking through the viewfinder. Try this at different distance settings, although in my experience there is rarely any difference, and when content, replace the accessory shoe, it's as simple as that!
If, after carrying out this adjustment, you feel the need to adjust the horizontal alignment, remove the four screws retaining the upper viewfinder bezel, and remove this complete with glass. You will see a vertical plate to the right of the lens, and this has two screws, the right hand one is used to alter the alignment. Only tiny alterations to this screw will result in dramatic changes in alignment, so go carefully, there is plenty of online info about the methodology of rangefinder alignment, or just use your intuition. Re-assembly is the reverse.
These are beautiful little cameras, made to standards of precision rarely encountered in mass production, and they have often survived the years remarkably well, but like any small mechanical device 40+ years old, they mostly need a bit of TLC.
Good Luck, Mike
