Your probably under the impression that a new alarm means new everything not so. It will only need the panel and keypad changed.
A local company should not charge more than £300-£350 max to switch out your system and that price should cover any issues they find aswell.
You might need a 2k2 pull up resistor across the 12v+ and the spk terminals
i could also be to do with the L1 and L2 jumpers i think the texecom speaker output is -v applied
Worked on the premia 9 still have a few out there.
Your system isn't compliant going by your pictures, no global tamper to zones been looped out with a staple the alarm on entry sounds to me like the door contact is stuck in the closed position hence going straight into alarm upon entry.
The...