Firstly apex seals don't "burst" they crack or chip due to age but more often from detonation (also known as pinging or knock) which is normally caused by too little fuel causing a lean burn situation.
The oem mazda apex seals use 3-piece design (2mm width) which are weaker than aftermarket 2-piece designs (also 2mm). Mazda (as i understand) uses a 3-piece design to offer slightly better sealing at low rpms.
Symptons of a chipped or perhaps cracked apex seal are low compression and/or difficulty in starting the engine / non-smooth idle (although the latter two can also be caused by other less serious problems).
When an apex seals breaks most often it will damage the aluminium rotor housing by scratching it or the seal itself may become lodged (rammed) into the housing. Either way your engine will idle very badly & be down or power in a BIG way. In some really bad situations it will also damage the apex seal groove(s) in the rotor too. Both the aluminium rotor housing & rotor will need to be replaced with a "new" one.
The above situation warrants a complete rebuild of the engine which can only be achieved by removing the entire block from the engine bay.
Therefore one of the most important items to be controlled in rotary engine useage & modification is correct (i.e. sufficient fuelling) as unlike a piston engine, RE cannot survive detonation. Some builders employ the use of 2-piece, 3mm apex seals which can withstand detonation up to a point. However, 3mm apex seals are a lot heavier and offer less sealing abiliities so are better used in a race engine seeing constant high revs - they are much less suitable in street engines, though can still be used with reduced performance.
