The + inputs are for limit switches… 
When a Ruida boots and attempts to home, it only looks for the home (-) inputs… After it completes the home, it will then monitor the limit (+) inputs and ignore the home (-) inputs.
- properly working tube
- clean and aligned optics
- proper focus
If you have these three they work… Best place to start is the beginning, so check that the tube is in TEM00 resonance or mode…
This is done at m1 on a test target. I test mine like this…
If the tube isn’t in TEM00 mode, it will never align properly and won’t work like it should…
Generally with an older tube, you can figure it’s the tube, but it can be an lps… You can get new tubes that fail this. From what vendor did you acquire the RECI tube?
When they manufacture tubes, the mirrors and other parts alignment is critical. When one of the tubes fail to test to specifications they generally don’t toss it… They sell it to vendors who put them in machines they sell or sell the tube at a better price than the manufacturer…
When you pulse this, make a very light mark. You want to see the Gaussian power distribution across the beam. You can’t tell much from a hole or a black spot. This is mine when I found it was not in TEM00 mode… This was dead center, three days later this is how it changed.
If you are in TEM00 then you need to properly clean, align and ensure proper focus.
Let us know what’s going on…
Good luck
