It's fine if the compressor is close to the walls (if it's within spec), That's part design.
But, it should never touch the walls, but have enough room to expand when hot.
But if there is a lot of play in the shaft, that's a sign of a turbo on its way out.
That might contribute to your underboost problem.
But can't really specify better, without some decent logs with me7logger.
Today I have read mistakes and I have received
17965 — pressure Regulator наддува:выход from regulation range (it is more than the top limit)
16490 — Pressure on an air intake/pressure => (G71/) F96 a doubtful signal
16621 — the pressurization pressure Sensor too low level of a signal
17956 — the Electromagnetic valve of restriction of pressure of pressurization-N75 break of a chain
