Sadly Rapier motors did go through various dodgy patches at times so if you have some old stock and are wondering if they are still OK, here is a guide, hope it helps.
Carefully examine the casing for any swellings, the motor casing sides must be perfectly parallel throughout the length. Discard any with swellings and treat the whole box and/or that year as suspect i.e. don’t try flying any in a treasured model, it could end in tears.
Once done with the casing, carefully examine the nozzle looking for breakdown of the pristine moulded surface. Any flaking or loose powder is a sure sign the motor will not ignite.
Despite the motor casing and nozzle looking perfect, there was a phase of burn throughs which could and did destroy some models, so test flying a few of these motors in profiles first could pay off.
There was a period when the nozzles were crooked, to check find a small drill bit and use the shank end to find one that just fits the nozzle (often 1.5mm in diameter). Insert the drill by the shank then lay the motor on a flat surface and roll it along, the drill tip should stay perfectly centred, if it wobbles you have a crooked nozzle. All is not lost as provided the rest of the motor looks OK it is probably usable, however it is best to mark the casing to indicate the side of the greatest offset (the side the tip points to) then when you insert the motor in the model’s motor mount orientate the mark to give down thrust. By which I mean; on an under slung motor the mark should be on the top and if the motor is mounted on the top of the model (as per the Jetex Wren) the mark should be on the underside, Rapier models often suffer from lack of down thrust so I found this quite handy at times.
If after all this the motor doesn’t want to light up with the fuse, drill into the nozzle hole using a 1.5mm drill as sometimes the nozzle moulding material blocks the hole. Do not drill deeper than 3mm or 4mm or you will risk a small explosion which will send shards of the nozzle forward violently and possibly into you or your model. The material that comes off the drill should be hard or fairly firm, if it is like putty then most probably the motor will not ignite.
The following user(s) said Thank You: rogersimmonds, Steve_B