Carving moved over 3 inches during carve

[Proctorw]

I was having Y error axis stall. Machine has 300+ hours. Replaced Y and Z bearings. No more stalls. Carved 4 crosses and the came out perfect. The 5th cross started carving incorrectly about 30% into the carve. Any ideas why? This was the 5th carve since new bearings.
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[bergerud]

My guess would be a Y belt slip. (Bit a little duller after all the carves and so harder on the belt.) Try retightening the belt.

[Digitalwoodshop]

Since it continued to track correct after it moved over.... I would say some dust in the encoder....

WAG.... Wild AL Guess...

AL