130 in a modification the block 124 may be reduced in cross section at a position where the heater element ends to provide a thermal barrier it will be seen that the oven is heated only over three quarters of its length see the solid double headed arrow the arrangement of the various components of the apparatus within the cabinet 50 is more clearly shown in fig6 a and 6b as can be seen the cabinet is divided into two sealed chambers by a wall 148 one chamber 144 lies between the wall 148 and the doors 56 and the other chamber 142 lies on the opposite side of the wall 148 to the doors 56 as previously mentioned a hinged cassette plate 35 supports all the pulleys the front section 148 of the combustion oven 92 and the belt 66 while the dispensing tube 88 the desolvator 90 and the rear section 124 of the oven 92 are supported by the wall 148 thus when the doors 56 are swung open and the cassette plate 35 is swung down the belt 66 is neatly withdrawn from the dispensing tube 88 the desolvator 90 and the rear section 124 of the oven 92 so that it can be inspected overhauled or replaced the chamber 144 houses fans 150 which draw air in from the environment and over the tape 66 where it is exposed to cool the tape 66 after it comes out.