Pumps don't always fail slowly, they can sometimes fail suddenly. I say try the pump, if it doesn't fix it you can take the new pump out again and save it as a spare. Something else to try, assuming your local laws allow you to and you know how to be safe, is to check the voltage at the pump when it should be running. If it has mains voltage present and isn't working it's the pump.

Over the last ~1 year I have had this inconsistent issue that when I start the machine it makes a hissing sound coming from the drip tray with some steam showing. It all stops as the machine heats up towards its set temperature (sometimes a bit after reaching the set temperature).

It sounds like some sort of valve is closing, like something is pushing in and closing shut (can't really hear that in the video).

This is issue is not consistent, it can happen once a month or sometimes once a day a few days in a row.

Has anyone come across something like that?

Thank you!

EDIT:
Apparently I recorded another video with the issue about 10 months ago but not sure if I asked the question anywhere, just in case it helps:

There are a few things that vent to the drip tray. The steam and coffee boiler drain valves are on the right side of the machine. Sounds like it is coming from the left side through. The 3 way solenoid vents there; however, I don't understand how it would result in a steam hiss. The other thing that vents there is the anti-vacuum valve. On top of the steam boiler there is an anti-vacuum valve. When there is pressure in the steam boiler, it acts on the valve seat and closes the valve, allowing the steam boiler to pressurize. When you turn off the machine and the steam pressure goes down, the valve opens and prevents the boiler from creating a vacuum.

2 ways to check if its the anti-vac valve.
1) when your machine is hot and this thing is hissing, is the steam pressure from the steam wand reduced?
2) unplug your machine and take the top off. Locate the anti-vac valve, it is in the center of the steam boiler with a thick, clear silicone tube coming out of it. Leave the top open, plug in the machine and start it up. When you start to hear the hiss, look at the tube coming out of the anti-vac valve and see if you see steam or water moving in the tube.

If it turns out to be the anti-vac valve, outwest coffee has them for $30.
https://outwestcoffee.com.au/index.php/ ... vac-valve/

Check back and let me know what you find.

Thanks lancealot. You were correct to assume that the hissing comes from the left side of the machine.

1) when your machine is hot and this thing is hissing, is the steam pressure from the steam wand reduced?

This morning the machine reached its set temperature without any issues (this issue is not consistent). However immediately after it reached its set temperature I checked to see if steam is available but turning the steam knob resulted with beeps and no steam. Tried a couple of times and then the hissing started just like in the videos (this time with the machine already warmed up) and after a few seconds it stopped.

I'll order a new vac-valve and test it out.

Thanks for your help so far!

Dear All,
New to the group.
5+ years BDB owner (2015 manufacturing date) and thank you all for great suggestions/comments.
In the attached link to picture with red arrow I noticed minor steam/water leak on the top with white 2-cable connected. My apologies if I missed at previous posts but I could not see whether this can be repaired by 007 o-ring or any other parts required. Many thanks,
CE
userpix/56218_img_3092_hb0428.jpeg

Yes, that is an O-Ring seal. I think its the smaller one, but definitely an O-Ring.

Yes 007 O ring (or possible 2x 007, can't remember, just put back the same number that are there)

Thanks very much.

In case any member interested in:
Breville BES900 or BES920 Coffee Machine Ball Valve Assembly SKU: SP0001713 is now available at Ewing Electrical appliancepartsrus (https://www.ewingelectrical.com.au). They have a flat shipping rate to US.

All I get there is a link to Breville's parts and accessories page. No ball valve there.