Top will not unlock - Philips Senseo HD-7810 Coffee Maker

It seems to be caused by pressure build up (not a vacuum) when the outlet of the pod holder gets blocked. There are three plastic bolts that slide into place to lock the lid as the lever is operated. Pressure forces the lid up and increases the friction on the bolts to the point where they won't operate. Solutions 1 and 2: First disconnect Senseo from the electric supply. Solution 1 is to press down on the lid to overcome the pressure and then operate the lever to unlock. Didn't work for me. Solution 2 is to get a table knife, not sharp, no serrations but with a rounded end, not pointed. Insert under lid just to right of pod holder handle, at an upwards angle of about 20 degrees to the horizontal. Then aim for the opposite 11 o'clock position on the closed lid. With a few tries the knife blade should slide between the top of the pod holder and the rubber sealing gasket releasing the pressure. Beware hot steam/water as pressure is released - wear gloves. Open lid, unblock pod holder hole with a pin, fill and heat resevoir and then flush through without a coffee pod in place.