I have a similar gun on the way, and zero experience, but I've been searching here for info and came across the following and saved it. I forget the member's name, but am pretty sure it started with an S. Anyhow, I'd suggest only removing the grips and clean/oil it before attempting disassembly. Here's what he said:
The 22 Sentinels don't have a side plate. You can remove the crane assembly by depressing the plunger in the front of the frame with a pin punch (with cylinder open)and pulling the assembly away from the side of the frame. To remove the lockwork assembly you then need to drive out the drift pin in the frame above the grips and remove thr triggerguard and lockworks. My advice is =don't. If you simply remove the grips(one screw in the bottom) you will expose the mainspring and you can cock the gun and squirt solvent into the lockwork that will drain out of the gripframe. squirt and cycle until things are clean then relube with a couple of drops of oil onto the hammer sear interface and a bit where the hand enters the recoil shield, where the trigger exits the frame and onto the mainsping. Cycle, wipe off any that runs out if you over did it , put the grips back on and go on with life.