This report is for informational purposes only. The cause has been identified and the problem has been completely resolved.

Customers have reported that silicone oil is leaking onto the sensor. This likely comes from the cooling paste that bonds the sensor to the heat sink and ensures optimal heat dissipation. Zwo offers cleaning instructions for a solution, see link:

https://astronomy-imaging-camera.com/manuals/How_to_clean_ASI_camera_and_redry_the_desiccant.pdf?fbclid=IwAR1n7uHUOH74--CUmh6vuh6fVm6v44WR5QPJPn-pKgxHuTOPk-Vlu_3F7xI

However, the warm-up phase is likely the far bigger problem. If you run at high TEC power (maximum cooling) and then simply shut down the camera, the thermal rise time is very fast if there is no software control. During operation, the TEC is very, very hot on one side and cold on the other. It's also thin—only a few millimeters thick. If the power is simply turned off, the TEC compensates by immediately transferring the heat to the cold side of the TEC device. In such cases, the very cold pad can heat up very quickly on one side.

UPDATE 11/22/2021

It has since been discovered that this effect can also occur when the camera is stored.

One of our customers has also investigated the issue and provided us with the following information:

The silicone contained in the heat transfer pad can outgas. Low molecular weight siloxanes (LMWS) evaporate; commercially available silicone elastomers contain up to 5% low molecular weight siloxane residues. One source of low molecular weight siloxanes is reinforcing and extending fillers, which are used to increase strength and modify certain physical properties of the final product.
[Source: http://sinoguide.com/event/brief-illumination-of-the-silicone-outgassing-from-sinoguide-technology/]

Under normal ambient conditions, oil leakage can still occur during storage, which is further exacerbated by thermal stress. In some optical instruments, siloxane evaporates and condenses as an oily liquid on the sensor.
[Source: http://sinoguide.com/event/lowest-oil-leaking-thermal-gap-pad/]

We are working on finding a solution and will post the latest status here.

Yours, Karsten