A Google search showed that this is a known problem. I've emailed Eheim support to ask how I could "fix" the problem -- I don't expect any useful advice, just wanted to make some noise about it. It is amazing that a reputable company would overlook such an obvious design flaw.

My question: does anyone know how I could saw a small wedge into the glass to accomodate the heater cable? If it's possible to smoothen the edges so it does not cut into the heater cord, that would be a bonus. If not, I'll figure out something to protect the cord, like duct tape?

I called CTE Aquatics in Timonium to ask if they had any glass cutting equipment. The lady who answered the phone said it requires a diamond tip saw, which they don't have.
Does anyone know where I can take the cover to get it cut? It's such a small cut that I can't justify purchasing equipment to do it.
Thanks,
Shireen
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Shireen Gonzaga
Cockeysville, MD