Platform not lifting - Suction

Any advice regarding overcoming suction effect that prevents the platform from lifting during calibration.
It was partially resolved by decreasing the amount of resin to a minimum when calibrating but when printing commenced the Z-axis just spins as the platform tries to lift. Because of the suction, my first thought was to reduce the platform lift speed to 80 mm/s; this lead to no effect.

I thought it may be related to long exposure time of the raft (120s per layer - external resin eSUN eResin Biopolymer) but the fact that it happened during calibration lead me to suspect the FEP film. This was relatively new, replaced it about 3 prints ago.

Another factor that may be at play is a badly scratched up bed platform. Could this result in the high level of suction or is it something else e.g. underpowered stepper controlling the Z-axis?

Anyone have a similar experience?