Trim and point into a safe area, try and fix by sweeping across the cockpit, if unsuccessful, proceed with PFL, keep reviewing wisdom of actions whatever you did.
Which is DODAR basically, which I like, but only in the briefing room. No, it doesn't belong - as a mnemonic, in the cockpit.
By an uncanny and suspicious coincidence, I had a phone call this morning from the student I did the biennial with. Two days after flying with me, he had a partial power failure on a BE23. He did as we'd drilled - pointed at good fields with the aircraft trimmed aggressively for best glide. Then sweep the cockpit looking for solutions, he switched tanks (as I'd drilled with him), power restored breathed sigh of relief, went home. On the ground they found the remains of a bee partially blocking the breather on one side - preventing continuous high power fuel flow but not readily detectable on the ground in a normal power check. He reckoned from realising he had a problem to solving it he lost 400ft.
He was in a good mood and felt he'd got value from his biennial, I reserve the right to act smug for the next few days.
G