SX1276 Calibration Routine

Dear Forum,

We are using an SX1276 Chip in FSK Mode and the datasheet states the recalibration in 868MHz mode is necessary once the chip deviates a few degrees.
Our SW developer implement this in 10 Minutes which we hoped will take care of every eventual calibration offset. he is saying now and then (1-5 times per day) nothing can be received anymore. He is missing a calibration workflow which says exactly which register need to be set and which not. Can some supply a manual or a flowchart on how to perform a calibration?