A rotary drive for a medical device , the rotary drive comprising: a non-magnetic rotary motor including a rotor coupled to a stator with a friction material ; a rotary motion encoder connected to the rotor, the rotary motion encoder being configured to generate a number of encoder steps measuring a rotational distance of the rotor; and at least one electronic processor , characterized in that the electronic processor is programmed to: determine at least one of a slippage value of the rotary motor measured during motor operation and a coasting value of the rotary motor measured after stopping motor operation based on a comparison of an actual count of encoder steps and an expected count of encoder steps, wherein a lower actual count compared with the expected count indicates greater wear status and wherein a higher actual count compared with the expected count indicates greater wear status; determine a wear status of the rotary motor which constitutes a wear status of the friction material based on at least one of the determined slippage value and the determined coasting value; and generate a warning to replace the motor when the measured slippage value and/or the measured coasting value exceeds a first threshold. a non-magnetic rotary motor including a rotor coupled to a stator with a friction material ; a rotary motion encoder connected to the rotor, the rotary motion encoder being configured to generate a number of encoder steps measuring a rotational distance of the rotor; and at least one electronic processor , characterized in that the electronic processor is programmed to: determine at least one of a slippage value of the rotary motor measured during motor operation and a coasting value of the rotary motor measured after stopping motor operation based on a comparison of an actual count of encoder steps and an expected count of encoder steps, wherein a lower actual count compared with the expected count indicates greater wear status and wherein a higher actual count compared with the expected count indicates greater wear status; determine a wear status of the rotary motor which constitutes a wear status of the friction material based on at least one of the determined slippage value and the determined coasting value; and generate a warning to replace the motor when the measured slippage value and/or the measured coasting value exceeds a first threshold. determine at least one of a slippage value of the rotary motor measured during motor operation and a coasting value of the rotary motor measured after stopping motor operation based on a comparison of an actual count of encoder steps and an expected count of encoder steps, wherein a lower actual count compared with the expected count indicates greater wear status and wherein a higher actual count compared with the expected count indicates greater wear status; determine a wear status of the rotary motor which constitutes a wear status of the friction material based on at least one of the determined slippage value and the determined coasting value; and generate a warning to replace the motor when the measured slippage value and/or the measured coasting value exceeds a first threshold. <EOS>