D BRITTEN

my omicron 7000 intruder alarm is giving problems. I think the panel is OK, but the outside bell box doesn't sound.I intend to first replace the bellbox, if this don't resolve the problem then I will replace the control panel. Or do you recommend that I just update and replace both items. I want to reuse the wiring and security devices. can you please recommend a suitable reliable replacement and give me some idea of the cost of the units. many thanks David