Bosch washing machine not taking powder

[foxhole]

Using powder in draws is very ineffective , it does not dissolve well and leaves a lot of waste sludge in the base of the machine .
Powder should be mixed in a jug of warm water and poured into drum before adding clothes.

 

[Johntheo5]

The two Zanussis work similarly.
The older (~10 years) opens the drawer bypass solenoid for 37 secs and then shuts it, it then opens the "drawer" solenoid for 1 minute 16 secs and the stops, wash commences.
The newer (3 year) operates the same way but for shorter periods, the bypass for 10 seconds, the drawer solenoid for 1 minute, wash then commences.

Theres a flap in the drawer that you close for liquid detergent and open for powder, is yours set up properly?

 

[Gossamer]

I left the machine running for longer this time to see the process as advised and it started putting water into the pre-wash drawer (I) which makes sense, but what struck me is how weak the flow was.
I'm starting to think the supply is the issue. Maybe there's a 'strainer' inside which is blocked with limescale??

 

[Johntheo5]

The main flexible hose will certainly have one, if not two strainers, the water needs isolating and the hose removed one end at the time, check/clean strainer(s).