Aargh.  Had first fail with 3YO Rocket Evoluzione V2 this morning.  SWMBO in early morning trance state made herself a stone-cold coffee without noticing the pressure gauge at zero. Needed to coarse-grind some beans, boil the kettle, and use the plunger - coffee needed before attempting repair.

To get at the element terminals the outer case has to come off.  Need to take care with this as you don't want to mishandle and damage the polished SS panels.  Element was open-circuit.  I drained the boiler into a tray by loosening the hot water wand pipe on the boiler end - didn't have anything handy to suction out the boiler from the top (ie after undoing the anti-vac valve). There's no room to safely get a spanner on the hex end of the element, but fortunately a 32mm deep impact socket did the trick.  Quick trip into town for replacement element and gasket, fitted it then bench test with covers off to check that it's filling properly/reliably (ie the element didn't blow because of another malfunction allowing it to run without the boiler at correct level) and check for leaks once it's up to pressure, then had the machine back in action by lunchtime.

A few observations from this exercise - and ownership so far:

Under the covers is really very impressive - the Rocket is beautifully made/assembled and laid out, with no signs of leaks, corrosion, or general aging. I guess that's a reason why they are quite expensive.  It looks like because of quality fittings/machining etc, if I need to do other work on it requiring more complete disassembly, then it should be straight-forward (not dealing with poor quality connectors etc). The machine has been used constantly for 3 years - every day.  There was a little bit of scale on the element and a teaspoon of flakes in the bottom of the boiler (dried, then vacuumed out) - I expected worse.  This is with Chch tap water, so YMMV. 
There was a bit of dust - in future I'll probably take the covers off every couple of years just to clean it out.  I've not needed to adjust either the pressurestat or the pump pressure, they've stayed in exactly the same range as when the machine was new.  

Disclaimer - I'm not endorsing DIY repairs and maintenance here.  If you don't know what you're dealing with - don't even attempt it.