If you can get the hammer back far enough to retract the bolt and allow the cylinder to rotate freely, do so. If not, proceed to step 3.
1) Remove the barrel and cylinder.
2) Introduce your cleaning liquid (spit, Ballistol, T/C No. 13, Windex, hot water, whatever) into the bolt hole in the bottom of the frame. Be generous.
3) Introduce the same liquid into the opening in the recoil shield where the hand that rotates the cylinder comes out. Again, be generous. (If the cylinder is still in place this may be difficult to do)
4) Generously wash out the hammer channel with the cleaning liquid.
5) Move the hammer back and forth as much as possible to work the cleaning liquid into the spaces between the hammer and the frame and into the internal action parts.
6) Repeat the above steps until the cylinder can be removed, then repeat again until the hammer is free to move full travel.
7) Disassemble the entire gun, clean, dry and lube the action parts and reassemble, being sure to lubricate the cylinder base pin.