cyendrey However, there is a very small gap/light leak where the edge of the camera body hangs over the outside edge of the EFW (EFW 2"x5).
This is a known problem with all ZWO filter wheels that bolts directly on the camera with the four screws. This has come up multiple times on this forum alone. I don't know why ZWO still keeps pretending as if it is the first time they have heard of it. I have even posted an image right on this forum showing a black electrical tape.
If you inspect the normal tilt plate that came originally with the camera, you will notice that there is an annulus trench, with an annulus foam inset. When you bolts the tilt plate on tightly, the foam compresses and blocks any leaking light. The foam fills in any imperfection (just like thermal foam fills in the gaps between a semiconuctor chip and a heat sink).
If you look at the filter wheel, there is no way to add an annulus foam. You cannot just add a soft foam piece since you need the annulus trench for the foam to compress into, otherwise the filter wheel will introduce a tilt.
There are only three ways out of this: one is to use electric tape which you mentioned, another is to machine an annulus trench yourself, and then add a 1mm thick soft foam annulus, and the third is to not attach the camera with those four bolts -- just use threaded tubes.