Question about Canon Auto Zoom 814

[Zain Hashmat]

Hi all, i hope you’re well. I'm a little new to super 8 filmmaking and I was wondering if someone might be able to confirm something for me or maybe give me some guidance? 

So, I recently bought a used Canon Auto Zoom 814 from Etsy and everything seems to be working perfectly except for something peculiar I've noticed when looking through the viewfinder. Everything seems to be so, well, dark whenever I look through the viewfinder. It looks like there's a filter that cuts the light quite a bit when looking through the it. Is this normal? I can barely see anything in low light conditions and it's a struggle to see anything properly when indoors. 

I messaged the seller about this problem and they told me that these results are normal because of the mirror reflex system on the camera. Does this sound right? If you have a Canon Auto Zoom 814, does it run darker than usual when looking through the viewfinder? Is this a normal issue with Super 8 cameras? If not, should I expect to see something else, maybe something brighter, when taking a look? Any advice or guidance would be much appreciated. Thanks so much!