Have you worked with alarms before 'b'?
Worked with thousands of flashguards Eric especially the old range your talking about
Whats probably happend is the resistors for the l.e.ds have blown especially if they started flashing fast before die'ing out or the pcb has warped a tad its good that the strobe and siren are working but i do reccomend replacing or at least opening the bell box maybe give the pcb a push see if that gets them flashing
If all fails replace it with the new flashguard xl burglars would just think the alarm was dead
Nick
September 2015