[iadom]

It’s unusual to see that amount of black bits from algae build up, but that’s what it looks like. If you pull out the detergent dispenser drawer you will often find it black and manky. Sometimes worse in soft water areas and often linked with using constant low temps and liquid detergents.
I make sure my machine does at least one 60degree wash ( towels, whites, bedding etc) every week. I also only use powder. Green box Ariel for whites and purple box for coloured.

You can also do a ‘maintenance’ wash every few months, if you can’t find enough to do a regular 60 degree wash, do a 90 degree wash without clothes and a very small amount of powder.

Bleach, soda crystals etc are of very little use. There are enough chemicals in good quality powder detergents to keep the machines innards clean as long as you hit 60 degrees once a week. The only real difference between the green box and the purple box or colour detergents is that the green box ones contain a bleach. It is however an oxygen based bleach that only fully activates at around 60 degrees. Dr Beckmanns Deep Clean is quite good at removing gunge from inside the drum if it is really bad, better that the Dr Beckmanns Service It.

Those sort of deposits usually only show if the machine has not been used for a few weeks as well.