My New Magnepan 1.7i's sound dull and lifeless on the top end...why?

I just bought a used pair of 1.7i speakers, in pristine condition and only 7 months old. I own a pair of .7s and wanted to upgrade. The 1.7i speakers sound bad. Dull, bassy, no high-frequency detail. I was hoping to get more low-end response, but I wasn’t expecting the dull, lifeless sound. I am very experienced in setting up Maggies. Magna Risers don’t help. Different amps don’t help. Tweeters in vs. out don’t help. Neither does moving the speakers and my listening chair help. I can get them optimized, but I can’t remove the shelf in the frequency response (about 5 or 6 dB starting in the midrange, so that the lower mids and bass are elevated). Is this how they sound? Is there a large variation from one pair to another? My .7s sound awesome in the same room with the same equipment.

@eatapc Hi. I am a former Maggie 1.7i owner. This is what I recommend:

1. Magnepans NEED subwoofers. They do. They are ribbon speakers with no air movement and no percussion. There is no slam. They need subwoofers. I added a pair of REL T/9i subs to my 1.7i and it revolutionized the sound. 
2. I agree the binding posts, fuse and jumper are steel plate garbage. I replaced the steel plate jumper and cheap fuse with Mike Powell’s silver upgrade. It’s a sliver humper and a silver tube replacing the fuse. Those changes greatly improved the top end. I am sure if you are handy enough and can replace the crossover and binding posts, more benefits will accrue. 
3. These Maggies need powerful solid state amps for regular driving, but also for headroom and dynamics. Schiit Vidars are insufficient. Amps like the Brystons and Pass Labs are good. 
I hope this was helpful. 

Hi Friends, 

So I am at about 250 or so hours with my new 1.7i's, and also experiencing the lack of highs, and sort of lifeless sound as well. Do they ever open up more, after more hours...or is this it?  🤔  They are quite slow sounding, and I have a McIntosh MC 252 driving them, on its 4 ohm Taps.  So weird. I'm  not used to Maggies sounding slow, as I've owned MG 12's in the past, along with. 5's, and these sound nothing like those.  So will these open more in time? Did the original post guy have any changes to his?  Really curious, and also wondering if I should start driving them hard and loud to get em to open shop.  Just don't know.  Thanks for any insight.  -Brian.