What did you see ?
If you look in the oil filler and work the clutch lever can you see the clutch plates moving at all ?
What did the clutch basket look like when you had it apart ? was there little ridges worn where the friction plates slide up and down in it ? If the basket is too worn it can cause the friction plates to catch and not disengage properly.
You can measure the clutch springs to see if they are still within their tolerance. ie now too compressed to release the friction and metal plates.
Is the clutch cable worn and now too long ? can you adjust it any more ?
If it has been a while since the bike was running i have had very sticky plates that need the to be forced apart by starting the bike in gear to try and release the plates.