The screens can be a bit lacking in snap, a good way is to start from infinity, pull in just past the point of focus, then rack back out just past the point, then fine tune on the back in. An old shooter taught me this, if you have a slight mis-focus due to operator error using this technique then the point of focus is slightly closer, which visually speaking seems less abrupt and jarring to the viewer. Also consider the most common Mamiya TLR focussing problem, search the web, over the years I've posted the same info about this camera. The foam surround on the focussing screen frame gets compressed and sticks, causing a very minute error. This leads to a very wrong 'mismatched lens pair' diagnosis, and all the incorrect ways to fix that 'problem'. I've 'repaired' soft lenses that had a non-factory shim placed on the threads of the viewing lens, removed the shim and magic, lens is sharp on a properly foamed body. I've posted how to do the fix many times. As a matter of course I refoam my 2 TLR's if I haven't used them very often, probably once a year.