CDs play from the inside to the outside of the disk (the opposite to a vinyl record). Smiddyburn/Flittin is a 2-on-1 disk so it's pretty full; the last few tracks will be right at the edge of the disk which is the part most vulnerable to physical damage. Check the rim and see if there are any cracks, prints or other junk.
The bottom side of a disk is the playing side but surprisingly, damage to the top surface can be more likely to cause playing problems. Check the label side too for any signs of damage.
Some makes of disk used to go bronze around the edges over time. Tracks that fell into the bronzed area would fail to play properly. This bronzing was found to be due to a fault in the manufacturing process and for a while it was possible to get these disks exchanged. (I had this bronzing problem with various John Martyn and Nick Drake CDs - though ironically by the time I got my copies replaced the albums had all been re-issued in re-mixed/re-mastered form so I went and bought them all again anyway!) If your disk has gone bronze around the edge then
this page should give you some more detail.
Cheers
Nick