When all else fails.....

.....read the instructions.

I have had my strimmer (grass trimmer) for many years now.  I am sure that when I first got it I did look at the instruction manual, but I cannot remember for sure.  Today I was having real trouble with the cutting line either not extending, or extending freely.  After struggling for some time, I finally went on line to download the instruction manual.  I now know how it is supposed to work - and I have also realised that I have lost a small spring which locks the spool and stops the line unwinding without restriction.

At least I managed to complete the job today, and I am contacting the manufacturers to see if I can get the spring from them, or whether I have to improvise.  I must also clean up the tool!