Whats gone wrong is about 6 channels on one TV started braking up didn't know why but I had a plug in signal booster so plugged it in next to TV and it worked, a few months later another tv started doing the same ( Strangely affecting different channels ) so I'm assuming its the amplifier in the loft.
First thing to suspect is the aerial and/or cables and connections.
Examine all connections. Remake any suspect ones. Ensure plugs are in firm and not loose. Ensure any hdmi and aerial cables are apart (cross-interference can occur).
Aerial: where in or out. What style? How old? External aerials may have an average life of around 12 years (some die quicker other last a lot longer). They can also be affected by external things like tree growth.
Pretty hard to find maker / specs but if the amplifier is this one
https://www.powersaver.co.uk/product/mercury-8-way-vhf-uhf-distribution-amplifier-amd08/ has 8dB gain (lowish but sufficient if the aerial is sound, working properly and supplies one TV at a time without any issues). The Full 20dB gain output must have a terminator plug (usually supplied) but could be used split two ways to provide 2 x 16dB gain feeds... or a 4-way split at 12 dB gain (cf 8dB gain for the main outlets).
You can test the aerial direct to one location by using a 'joiner' barrel and by-passing the amplifier box.
Check that a mobile mast has not launched close to your location and causing interference at
https://restoretv.uk/ They can supply filters etc.,. if needed free of charge to you.
I'm not convinced a new amplifier is the correct solution.
NB Most TVs have signal strength (and quality) metering diagnostics built in. It's often worth using them to see if a pattern exists on the different frequencies received.
