You need to get hold of a multimeter and measure the resistance between the stator’s white and green wires, which should return a figure of about 400 ohms. You can get additional info on testing from various places, incl. Cambridge Lambretta’s website, Sticky’ Manual, etc.
http://www.lambretta.co.uk/downloads/el ... cprobs.pdfLT coil failure is all too common and something that many have suffered. It doesn’t seem to be exacerbated by other components and typically nothing else will need replacing. One thing to watch out for is that some failing LT coils still give reasonable resistance figures and sometimes perfectly good stators can give low readings so even multimeter testing might not identify a problem. This does,however, mean that substitution for a known good stator is a very good test of the stator in general.
If multimeter testing does give you a low reading then your options are to replace the LT (if your soldering is good), upgrading to a better LT coil (Indian stators have an LT of one size, Italian and BGM use another... they are not interchangeable without modifying the stator plate), replacing the stator (various options but some are likely to suffer LT failure again) or even a new option of replacing the coil with a new CDI that sources it’s power from the lighting circuit (it doesn’t matter if your LT has failed.. not that these have just been developed and have yet to prove themselves long-term, now available from Readspeed). As such solutions range from about £10 (Indian LT coil), upgrade coil (£20-30 ish, Indian stators needing modification to use them), stator replacement £35-100, change to new lighting circuit CDI (price unknown but I believe they are now on sale. Lots of options to choose from.
My personal experience, and speaking as someone who too often fixes failed stators for others, is that replacing a failed LT with another cheap LT typically leads to failure again. Many people in my club have had very good reliability from use of the BGM stators. Anthony Tambs (do a search) is producing a stator that is getting good reports. I’ve been lucky enough to trial one of Readspeed’s new CDIs and can confirm that they do work but even I must acknowledge that this is a new product and I’ll want 5000 miles under my belt before I can even start to comment on reliability! Also don’t forget that others have made a complete swap to other systems (e.g. Varitronic, etc.) to get away from the common reliability issues (other features besides)that many suffer from cheap electronic kits. However............. my ‘go to’ fix, which has proven its worth time and time again is an upgrade to a better LT coil (there is an upgrade thread on one of the forums).
Good luck, whichever way you decide to go... and, yes, testing is your first step.
Adam