Has anyone had a stuck MAP vernier before and if they did, how did they deal with it? The vernier in my 231 jammed on Sunday for 30 minutes, right after levelling off at top of climb at F130 and throttling back. I could depress the button on the vernier knob but only rotate the knob about 1/2 a turn. I couldn't push the knob in or pull it out at all. The resistance in the vernier knob to rotation increased as though I was winding the cable up with the other end jammed. Not knowing what may happen if I broke the connection at the other end of the MAP cable, I didn't try to force it. After fiddling with it for half an hour, it eventually freed up. The MAP was stuck at 27 to 29" so I was able to set RPM and fuel flow to suit so the engine ran OK, but I didn't fancy my chances of landing with 27" of MAP. My plan, had the knob remained stuck, was to kill the engine at 1000' and land dead stick, with help waiting to tow me back to the shop. I had flown through some light icing on climb but it had melted off the windscreen and wings once clear of cloud. Any comments would be appreciated.