Thank you. Your mounting is looking good.
Could you also provide other details about the model (ESC, BEC voltage) + 4ds settings file.
We have developed new firmware and software for checking one possible reason for the problem.
It is identical to official 2.5.2 but it has check test whether the unit is running from Backup oscillator or External oscillator.
Backup oscillator is less precise and could cause the problem theoretically. Normally all units are using External oscillator. But in case of malfunction backup is used so that basically nothing changes for pilot.
If backup is used, you will see it as the first event in the Spirit flight log.
You will just need to flash this firmware:
http://spirit-system.com/dl/fw/spirit-fw-2.5.10.4dfand use this software:
http://spirit-system.com/dl/settings/sp ... -win32.exeThis will help us to investigate the issue a lot and then find a solution.