MrBaggins wrote: It's as if the water is having to force past something that is slightly stuck. I'm fairly sure it's coming from the lever mechanism as the handle also gives a little shake once the machine is able to push past to 9 bars.

Oh!
As the pump gauge shows about 9, your pressure beyond the gicleur is just getting high enough to start unseating the preinfusion valve and squirting past... Thanks for mentioning the control-lever wiggle, you can sometimes feel that when the preinfusion valve opens if you keep your hand on the lever. So, absolutely nothing to worry about, just water squirting past rubber on a spring loaded valve. Changing the preinfusion valve's rubber face might make the noise go away, but there's no need to care.

Nothing in this picture bothers me.

The dark spots on the copper tubing are oxidation of things that are protecting the copper as much as staining it.

The crap on the threads between the solenoid valve and check valve is just thread sealant applied in assembly.

MrBaggins wrote:I'll have a look at the group head valves first then see about adjusting the pressure release valve. In regards to the pressure release valve, should that turn be clockwise or anticlockwise?

I have the same sort of valve in my Synchronika (my Sync looks a lot like your 700). However, I've never messed with it, so can't speak with any authority. I do know that it is a spring-loaded ball valve, which would suggest clockwise to tighten. But, what the heck, if you put a hash mark on it, there's no danger in trying it one way or another. In fact, sometimes valves of this sort trap a bit of crud and get noisy. The first thing to do with them is turn them significantly past either side of the desired set point in the hope that any crud would be crushed or released. If that does not work, then take them apart for cleaning. Bear in mind, I'm not suggesting your valve has anything in it. My suggestion is merely to tighten it to see if the noise goes away. If it does, then you know that the set point was too close to the set point of the pump bypass pressure.

Thanks guys, with a few more shots and some more back flushing the noise seems to have dissipated. The brew boiler and the steam boiler are all heating and and maintaining temperature very well now.

I suspect I might need to open up the group head at some point down the line to give it a bit of a clean. But I might just sit back and enjoy some coffee for a bit first.

Once again thank you all for the comments, I feel I learnt so much more about the machine troubleshooting it and reading all of your replies.

Cheers,
Nick