DIY Guide to Dismantling JUNKERS 11-2B 23 Heater: Leaking Issues, Quick Couplers & Burners

Hello,
I have a JUNKERS 11-2B 23 heating stove.
Two days ago it started leaking.
Probably somewhere on the back of the heater.

Here's a question. How to disassemble the heater on your own?
I took the sensors off the heater, and so did the quick couplers.
Pipe removed in advance. I assumed that after unscrewing the two screws on the top, I would be able to lift the heater with the upper sheet metal element up and remove it.

The problem is only with the quick-release couplings that are under the handle ("trumpet mouthpieces").
It seems to me that I will not be able to just take it out because these quick connectors will not pass between the hook and the burner.

Here's a question. How to do this without touching anything related to the gas, which is basically everything below the fuser.
Is it necessary to remove the entire furnace from the wall or remove the burners to remove the heater?
After disassembly, I plan to visit a service technician anyway, because this stove is already 6 years old and probably something a service technician will find for improvement.
Of course, also for security reasons.

Added after 1 [hours] 39 [minutes]:

I was able to find a fuser removal instruction in Russian on YT.
It is true that it is not the same model (and in addition BOSCH), but the construction is very similar.

http://www.youtube.com/watch?v=Sfu5d8sNcqI

Heater and burner removed. Both are not in a tragic condition, but it should be cleaned.

Which seals to replace (disposable)?
I have such:
- left hand hose (drain)
- right tube (inflow), there are two seals here
- burner gasket

Somewhere I read that it is enough to lubricate those for water with technical petroleum jelly.

Water, due to high pressure, should be replaced with new ones. Gently grease the burner gasket.

I cleaned the burner and descaled the heater.
The burner, surprisingly, after 6 years was not in a bad condition. Nothing was clogged.
There was no scale in the heater either.

There is only one problem. I dismantled the heater due to a leak in the back of the heater.
Water was dripping from the back of the heater on the left side.
Unfortunately, I did not find a hole anywhere. If the heater had no patina, it would look like new.

I flooded the tub with water all the way to the quick couplers. I attached a mattress pump to one hole and plug the other hole.
I was counting on at least small bubbles. Thread. Absolutely nothing.
Maybe this pump is too weak, but I have no other idea.

How can it be checked otherwise? : /

I'll try to get it under the water tomorrow evening. One hose is flexible, maybe I can tilt the heater and look at the back where it leaks.

You need to connect to the mains water. The pump on the mattress generates too little pressure.