hmmmm im having a similar problem with my cabriolet

endless list of problems, but after being off road ALL SUMMER i started it up all excited tons of blue smoke, had a bit of a head scratching session, found a valve guide pushed in, cant see how it happened or why it didnt smoke before but ANYWAY got a new valve guide fitted, £80 later and head re-fitted, it starts and smokes for about 30 seconds then is fine

the engine was rebuilt 3.5k ago??????????