Well, typically cubes with looser tensions have a tendency to over flex and lock up occasionally. Perhaps you could try tightening the screws a quarter turn each.I've had my MF3RS for about 2-3 months now and I've noticed it's locking up a little, how can I stop this?
It could also be to do with your tuning style. If your TPS has increased over the last couple months, your turning might be more aggressive than it used to be, which could be the cause of the lockups.
Try calming your turning a little to see if that affects the lockups.