Preventive maintenance screws up PINDA  

Preventive maintenance screws up PINDA

I have an i3 MK3S which is a year old and has been printing great!  I decided to do some preventive maintenance and went through the list on the Prusa site.  I tightened every bolt and screw, including all those on the back of the hot end.  Full cleaning and lubrication of rods.  I opened up the Einsy-case and tightened all the screws.  I found that the Y belt was a bit loose and tightened it up.

The problems started when I ran the Z Calibration.  The second calibration point the nozzle didn't stop and went all the way against the print bed.  The PINDA had not triggered.  Strange, I thought.  I lowered the PINDA by a tiny amount and reran the Z calibration.  Now it goes past the second calibration point but does the same thing on the 9th and final calibration point.  I checked the PINDA sensor and it read 0, even with the nozzle against the bed.  But it seemed flaky and would go to 1 if I moved the PINDA at all.  Also it only seems flaky when the hot end is at the top right (last calibration point).

I tested the PINDA by putting a screwdriver up against it and it seems fine.  No flakiness observed.  But this is with the hotend in the middle.

I am looking for suggestions on what I might have done.  My first idea is that tightening all the bolts on the back of the hot end was not a good idea.  This might have pinched the cable from the PINDA.  Second idea is that there is a partial break in the PINDA cable, anywhere along its length.  Third idea is that by opening up the Einsy-case I somehow messed up the PINDA connection.  I will open it up again and check the connection.

Any ideas on what the problem might be?