arse! taken so long to catchup that i've a) forgotten everything b) run out of time!
sorry to hi and not even bye last night, mil needed entertaining! i'm actually quite surprised at how relaxing it is with her here. i'm now wondering if in fact its fil that causes the tension
anyhow vg in answer to your question...
i've got some questions first...
when was your machine working last? has it been moved about/knocked since it was working?
if it was working recently, was it with this bobbin of thread (the thread in the bottom) or a different reel?
things to try...
find another bobbin and try sewing with that
if that doesn't work either it could be your tension. what machine have you got? (make and model please)
are you using the same type of thread for the top thread as well as on the bobbin? even if same colour, if its different, it will cause problems with your stitching
have you tried taking the bobbin out and putting it back in again? it could be that the machine isn't threaded right. might be worth taking the top thread off as well and starting again. whilst you've got the bobbin out, have a look in the compartment to check no bits of fluff in there
have a look at the thread on the bobbin, does it look like its wound correctly? it should be reasonably tight so if you prod it with a fingernail and it goes in, it might be too loose (or do i mean lose?!)
i'm logging off now but give me a call if this doesn't make sense! i'll try and pop back on later to check how you're getting on