Simple to replace:

Removal:

1. Remove  the 3 electrical connectors on the solenoid
2. Remove the silicon tube from the top of the valve.
3. Remove the C clip with plyers, and pull out the pipe, on each side of the valve.
4. Keep the  C  clips so you can reuse them.

Installation: 

1. Insert the new o rings onto the PFTE pipe, on each side of the valve.
2. ⚠️Take note of your existing valve position - by taking an image of the existing solenoid.
3. ⚠️ Pay particular attention to the no1 position and the no. 2 position on the valve. Make sure position no. 1 is in the same position after you are done. The valve is one-way and must be in the correct position - otherwise, you will have to reverse it. 
4. Push the PFTE pipe right into the valve and lock it with the old clips - push back in by hand.
5. Insert the silicon tube back into the valve
6. Insert the wires back into the solenoid.

When finished if the circuit is not working probably the solenoid valve needs reversing.

💡If you need to replace the plastic fitting that came originally with this fitting.

You can use these fittings - they are steel so will last a lifetime

See

1. Sage/Breville Push fitting 1/8 x 4mm
2. Universal Fitting 1/8F x 1/8F
3. PTFE Sealing Tape

1. You will need to cut off the brass olive that is attached to the existing Ptfe Teflon Pipe
2. Insert your Ptfe Teflon Pipe  into the push fitting.