Chain looks awful slack ??
 

Yesterday I noticed my chain looks really slack and was considering adjusting it today, however it's the original and done 14000 miles, do you think it may be needing replaced rather than just adjusted ??

If it's lose .... Tighten it.....
see how well the chain fits the sprockets
if the any tight spots in it...or the sprockets are
showing signs of hooking teeth...

At 14,000 miles most lightly.. tighten it , lube it , ride it...




...

Play of the chain should be 50-60mm, that's more then on an average bike.

Regarding service manual :

1. Measure 15 section of chain - length limit 240,5mm (9.46 in). (while measuring push down drive chain to increase tension, measure the length between 1 and 16 links). If longer - replace chain.
2. if see any stiffness, some links stuck and lubrication doesn't help - replace chain.

If sprockets are worn or bent - replace chain and sprockets as set.