I have some sympathy with most of Adrian's posting, but I do not share is stance on the need for airtight bellows.
While the bag, the chanter, the drones and the blowpipe need to be absolutely airtight a slight leak in the bellows can actually be beneficial for beginners.
If the player operates the bellows using a full stroke to refill the bag, and then waiting until another full stroke is needed, the effect of a small leak is minimal. If on the other hand the player is continually "snatchin' at their bellasis" (as Joe Hutton would have said) then a small leak makes playing very difficult.
However, if the bellows leak sufficiently to cause problems then they must be fixed.
my $0.02
Barry