There is a product that is designed to remove calcium. It is very effective, but I cannot remember its name. I have purchased it a number of times at an Ace hardware store. It has a goopy consistency and comes in spray bottle. You can spray it on and use a toothbrush to clean it up. If it is calcium this product will clean it up whistle clean. You may also want to pour it into the lift arm to clean out any calcium buildup you cannot see, and then rinse at least three times with lots of water.
If the deposits are not calcium then it may not remove the deposits. I would then remove the lift arm unit from the drum rotation unit and soak the arm part in a pale of water mixed with Processor Clean II for several days followed by at three good rinsings. This stuff can clean almost anything if you are willing to soak it for an extend period of time. I would even recommend getting a large enough container so that you can soak all chemical piping in the lift arm assemble for 24 hours independent of whether the calcium was removed or not. This will clean up any chemical residue that you cannot see, but may contaminate your process. In general, color developers are very sensitive to contamintion and can result in less than optimal results, all of which you may not be able to detect with your eye.
I have a Fujimoto CP-51 and periodically I remove the rollers and soak them for extended periods of time in Processor Clean II. The nice thing about Processor Clean II is that it is a non-absorbent detergent so you do not have to worry about any contamination from the cleaner.