I second the suggestion of mwooten
And remember that quite often RF suffer from backslash focus.
If you miss the focus turning the focus ring, and you pass beyond the right focussing distance, you should not turn back the ring. Just reset the ring to infinity and restar again. If you simply turn it back, you should get focus issues.
I hope i described it correctly.
Best of Light!
Epson RD-1s, Leica M2, summicron 40, 50, elmar 90, Fed 3b, industar 22, 61 L/D; jupiter 8, 9, 12.