Losing accuracy with each jog

My wife and I purchased a 1000mm X-Carve a short while ago, and this weekend we started to put it through its paces. Assembly went all right, and our first test carve seemed to go all right - round parts were round, not apparently stretched, depth seemed accurate, all in all it was pretty cool!

Today I tried doing something where accuracy was somewhat important, though, and I noticed that it was a couple centimeters longer than I expected: I was aiming for 52cm wide, and it came out around 54cm wide.

I started troubleshooting by ensuring belts were tight, and they seem to be very tight, although I don’t have anything by which to measure the tension.

I did some experiments with jogging after reading some people suggesting that you change the steps/mm setting. Currently I have the default settings: 40 steps/mm. I found that when I jogged a long distance in a single motion, the result was very accurate: a 600mm jog seemed to be almost exactly 600mm as far as I could measure it. However, if I split that jog up into a bunch of smaller jogs - (60) 10mm jogs - it ended up not at 600mm, but at around 620mm. It seems like this is the problem, that the errors seem to compound with smaller motions. Of course, I could be way off base here.

I was wondering if this specific symptom would be enough to help someone more knowledgeable diagnose the problem quickly. I am a bit overwhelmed by all the new things to learn with troubleshooting the X-Carve, and would appreciate any guidance. Thanks in advance!

Thanks - I just finished skimming from beginning to end. It looks like there might be some configuration variables that could help, but I didn’t see anything quite matching my problem. I will try playing around with some of them and see if I get any better results.