Always had really good results cleaning these  - cold or warm using 6.5 - 8 ph MS.  I also use the CFR 3 & 5" hand tools which work best around 300psi   ish,  try opening a vac hole it will clean much better and reduce the grab effect where vac locks onto filling material sometimes causing a mini flooded area, not really sure why this should happen on the enclosed cfrs think its just the grab effect when youre getting a bit tired or lazy with tool technique..?  Dry passes or dry hand towelling after can help if you feel you have over wet.  Or you could always setup a fan as you are extracting - Dont forget your acid rinse if using high ph gear...
Good luck
Stu