Grunfos 15/60 CH Pump Cutting out when hot

I have a Myson Midas BF Combi. CH pump was replace 9 months ago by Grundfos 15/60. Worked fine until recently when it has started to Cut out after 10 minutes.

Basically, from cold, the pump works fine. When disconnected it has a set resistance (electrical continuity). After 5 to 10 minutes (by which stage the pump is hot) it stops pumping. There is still a 240v feed to it from the relay board at this time. Electrical Continuity is no longer there. Switch off and on CH, no change. Leave for 30 minutes until cold, still no Elec Continuity BUT if I now switch CH on, pump springs to life. If I switch off before it stops and test Continuity is restored.

Is this a fault or is it a result of something else? If I buy a new pump is it likely to re-occur? I know I have light sludging, but it is not that bad.

PS no longer have receipt for pump!! Any Ideas, as I do not want to spend £50 on this if it is likely to fail this winter - the boiler is 14 years old and I am undecided if it will be uneconomical to keep repairing!

Thanks, Ant

Do what everybody else does - flog your dodgy one on ebay as "Nearly New"!
Not heard of a pump doing that before.

Thanks ChrisR!! Well this goes a long way to answer the question of whether there is an automatic cut-off inbuilt into the pump. The Ebay Route could be the favourite or maybe just buy another of the same spec and take this one back after a week saying it was the wrong one! If only I had the nerve!

Thought at first that it may be the capacitor but after rattling my other brain cell a bit I reckon it could be a break on the pump windings.So rare a fault that I havent come across it but I know it can happen.
Ring grundfos up and see what they say about it. This link might be useful http://www.grundfos.com/web/grfosweb.nsf/Webopslag/F9309303E11B9A4E41256A1600500986 Its the page where they boast about after sales service and has a contact link at the top right

Would be very interested to hear what they say.
Reports of their customer service are not good, generally!

The connection box on the grundfos is secured to the pump body with two torx screws, one of which also earths the connection box. The connection box jacks into a socket (pump windings are terminated into this) located in the casing.

You could loosen the torx screws and check for continuity (using a meter, NOT a neon tester) while moving the connection box. You could examine the socket for arcing (which would suggest poor connection)