Z axis too high to start

Going nuts trying to figure this one out... After running fine for months, the Z axis on the Prusa i3v is now starting too high up above the print bed. I have re-leveled several times, but it does not help. This is affecting not just new prints, but code made months ago that has always printed fine.
Slippage in the rubber tubing joint between motors and lead screws would lead to a lowered head, not raised, so I guessing its not that. Anyone have any other ideas on where to look? It seems to be a repeatable height so it's some sort of offset based on the height of the limit switch??

There is a setting to offset the home position away from the endstop/limit switch.
Check if you have some value set there.

No value set in the offset in slic3r. Checked (most?) of the obvious stuff first. Also, as mentioned, its affecting code that has been working for months, so i figured it was probably the printer?

Before you start a print job do you home the z-axis and test with a piece of paper between the nozzle and heat-bed?
Then when you start to print and the printer homes, what happens next? Does it just start higher than it should? By how much?

Slicing with Cura the standard start code homes, raises the head, primes the head then lowers back to print.
Slicing with Slic3r the standard start code homes, leaves the head down and starts to print.

Steve

---

My updated Instructable on our Prusa i3 Build
[www.instructables.com]

Check the endstop sensor, when mine started "acting up" the home position was getting set at 50mm above the bed!