Need help: LinuxCNC suddenly started cutting oversized contours

Hi,

Need some ideas for what else to try. Had my LinuxCNC working this January using EMC2 LinuxCNC postprocessor.
Attached picture of what the set-up looks like.

I'm cutting with a 1.5mm downcutter bit and I specify the radius is 0.0492 (slightly under so that my pieces are a little tighter fit) with no radius offsets hardcoded.
It cut different files all over my cutting area in several locations and all fit perfectly.
Didn't use my CNC for a month.
March I tried to load in a file and cut without changing anything. No pieces fit together. It's almost like they're oversized.

I've checked the tool table and config files of my cncrouter and nothing should be adding any offset.
The closest I've been able to come to getting my pieces fitting together again is by saying I'm using a 0.025 in diameter tool instead of the 0.0492 in that originally worked.
I've cut loads of sample pieces messing with the PQ/G64/G61 smoothing, trying the EMC1 post-processor, tightening all screws/belts/coupler set screws.
We tried changing cutting contours clockwise if it's an outer shaper and CCW if its an inner. Didn't have to do that before to have perfect fits, but this didn't result in a solution either.
Nothing to explain.

My dad has a CNC that runs the standard Tormach g-code and we use the same file. Only difference is the post-processing and cncrouter itself.
His cuts the same file perfectly at 0.0492in as mine used to. Simulation shows it working no issues.

If anyone has any ideas of what else I can try, please let me know. Thank you!

I would be suspicious of the mechanical part of the process.You might be able to check an old file against a recent file to see if the numbers are the same and if they are,it isn't the control software at the root of the problem.It might be play in bearings that have done a considerable amount of work or bolts in the structure that have fretted on surfaces and allowed a little flexing to occur.A spanner check of the whole machine and an assessment of the bearings and drive mechanism would be my starting point.

Have you try a new bit? Did the temperature of your work space changed? At this tolerances a bit deflection or sharpness comes to play as well.