Hi Laurie
I think Phil and I are talking about two different things.
Most powdered detergents contain 30 to 40 % sodium carbonate..AKA washing soda. You haven't been using commercially made laundry detergents. You've been doing the Ivory soap thing!
What I'm proposing is using a full cup of washing soda by itself (full strength) in a attempt to clean out the machine. Since you have a Front Loading machine.. I'd pre-dissolve this in hot water before adding to the dispenser.
I'm not suggesting that you do this continually, or that you add washing soda to powdered detergent since it's already contained therein.
Phil is making a very good suggestion in that whatever you chose to clean the machine with, that you run it with shop towels, rags ect, so that whatever you clean it with, gets dispersed to all sides of the tub.
When I helped a friend clean her machine (she had been a liquid detergent user with cold wash and rinses) and we where dealing with a Top Loader and had the advantage of filling the machine with hottest water, adding a cup and a half of Washing soda, letting it soak a while, then allowing the machine to go through a full cycle. We were able to see what the soda broke loose, and it started producing suds, with NO detergent added! Since her machine drained into a laundry sink instead of a stand pipe, we were able to really able to see what came out. This is what worked for her.
I'm not recommending that you do this all the time. Or for you to make habit of adding washing soda with every load. If you get the above Persil Pearls you won't need to.
Personally.. Occasionally I only use washing soda is when I'm using a liquid detergent (P.H neutral) and think for whatever reason I want to boost alkalinity. In that case I may add two Tbls only. (Also pre-dissolved)
"Occasionally" being the operative word here.