Michael,
How comfortable are you with taking things apart?
Nearly all of the reasons for a 15 minute brew cycle come down to only a few, easily fixed reasons.
Here's a few things to check. Some may not apply to that machine - I don't know it personally, but live in a city in which when you drop a glass of water, it's even odds what breaks first - the water or the glass...
1)If a chunk of scale has broken free and lodged in one of the water jets or is partially blocking the water line to or from the heating element, this could cause the problem. Solution:
Check the jets first, then check the lines. If you can't even blow air through them without real effort (disconnected at both ends) then that is probably the problem. If the chunk has lodged withing the heating unit itself, only time and very cautious use of acid and soft tools will get it out. Lots of time. Remember that vinegar attacks aluminium. Oh, could some coffee grounds be blocking something?
2) A heating element may have come loose. Not likely, but worth a check.
3) Thermostats almost never fail this way, but I have heard of weirder things. If one is cycling very fast, then that almost always means either a blockage or
4) Water is not making it out of the heating loop and into the pot. Most systems (sorry, I just don't know yours) use some sort of check valve (often just a little plastic ball) which is very very sensitive to blocking by scale. If the ball is blocked partially open or shut, then the water won't easily get out of the heating element, the thermostat will register a very high temperature and cycle on and off. Check valves are never complicated to find and inspect - they will rattle or when disconnected, permit you to blow in one direction but not at all in the other when working correctly.
5) Stupid one, but, hey - have you checked whether you have a tight electrical connection at every point in the machine?
6)Many machines have a simple device to prevent water from dripping or flowing unless everything is exactly in the right place. Has some part of this system failed?
I imagine you would get tons of good advice specific to your problem if you posted a pic or two.
Good Luck!