The surge protector is on the main nte5 itself (it's the small item which looks like a small diode on newer nte's or looks like a capacitor on older nte's with an earth terminal) you woun't affect the lightning protection with the removalof the face plate, in fact unless there's corrosion in the face plate then theres no difference to having the plate on or off if ther's no wiring connected to it.
To get the download speeds your getting at such a high downstream attenuation is impressive I wouldn't think your much above 63.5db if any higher at all. The only thing which may help is if there is another cable on your e-side with a lower line loss and a spare pr which yours can be switched to. But it's down to your ISP if their willing to raise a broadband fault to get this looked at ie are they going to look at this a s a fault.
Had a fault last week, From the cab the original line loss was 66.5db, got another pair at 58db to the cab but in this case the customer wasn't getting sync at all.
The only other thing to look out for is if you have an rf filter before the nte. Look out for a small box before the nte(white unless painted over) about the size of a box of matches. If you have one then chances are its a straight forward connecton block. If you can see the back of it (eg if in an attic and not screwed down) does it say rf2 (rf3 is ok with broad band) otherwise you could look inside but be carefull,
IF YOU KNOW YOUR CONNETION OFF BEFORE THE NTE AND YOU NEED TO GET AN ENGINEER OT TO FIX IT, THIS IS CHARGEABLE.
An RF2 is marked on the inside as well but the cables can obscure this, so what your looking for is 2 small black cylenders only about 4-5mm in diameter and about 8mm high.
If you find such a filter then you need to get you isp to get an engineer out to change this for a rf3. Because if you have an rf2 then this should stop broadband getting to your nte at all unless its corroded or your close enough to the exchange that the signal blasts its way through so you've got a bit of some thing. No line test will see such a filter, the only way to know if ones there is to physicaly locate it (still itching from those attics from saturday
) of if your a moderate to fair distance from the exchange and you've got some sync, in which case you havn't such a filter.
The other type of filter that will cause the same problem is an old style alarm filter/splitter. It block it lives in is one about 60x80mm ish. slightly curved (almost like a bar of soap) under the cover a large metal thing with about 4 sets on input & output screws, same situation
