Follow up:
I was finally able to run my job successfully.
All the issues I encountered was due to the spools binding on the arms.
I am confident that the spool to arm fit got worse as time went by due to environmental conditions.
The initial fit of the spools to the arms felt snug but I could rotate the spool on both halves of the arms smoothly. Subsequent disassembly showed they were very tight and binding.
Increasing the clearance between the spools and arms (sanding and polishing the spools inside circumference) resulted in both better calibration and eventual success in running jobs.
I am sure the extreme conditions here in Florida coupled with the fact that I am running my machine outside (under cover) resulted in the plastic expanding.
Some of the signs this was occurring include the following:
- Stress marks on the spool teeth.
- Low fitness values when calibrating
- Position errors when the sled moved to the outer areas of the panel
- A well-defined ridge on the inside of the spools when inspected after disassembly
- Difficulty spinning the spool on the arm halves when fitting.
None of these issues were present after initial assembly.
Not aware of what kind of plastic is being used but I am aware that both nylon and polycarbonates absorb moisture and that seems to be what is occurring. A looser slip fit between the spools and arm halves would help alleviate this problem.