Paranoia haunts me sometimes and hope I'm not falling for any cyber-scam here but would like to help...
If this thread is legit - pardon my concern; get the feeling and thinking you may benefit from someone in your area that has familiarity with Cox engines and/or control line - hope I don't come across as a prima donna as there are many more talented than myself - just happen to really like Cox .049s.
New Cox airplanes included an owner's manual that provided the user basic knowledge that I think would be beneficial here.
If you don't have one, there may be better info out there than this, but I found this Cox universal operator's/troubleshooting guide after a brief search that may help explain basics here:
http://www.mh-aerotools.de/airfoils/...ting_guide.pdf
Not sure how you have the flashlight housing configured, but the two batteries need to be wired in parallel (1.5V) - not series (3V). 3 Volts burns out the glow plug.
What you're doing should work to start the engine if you have 1.5V at the clip with a functioning glow plug.
With the piston at BDC, a functioning glow plug will allow you to see an orange glow reflecting out the slits in the cylinder.
No need to take the glow plug clip apart, as gene6029 said, clip can rest atop glow plug - doesn't have to go between fins.
Including pictures of glow clip attached to engine and battery types I use; NiCad soldered to clip is not the best arrangement and only delivers 1.2V but is portable - also fuel bulb that is handy for fillups and priming of engine at exhaust ports.