thereby contain an electronic circuit assembly 60 a top cover 80 and a bottom cover 82 sealably enclose the cavity 58 see fig2 and 5 the circuit assembly 60 receives inputs from first and second electrical proximity sensors 62 and 64 the first and second sensors 62 and 64 are positioned on the concave arcuate surface 54 of the housing member 14 each sensor cooperates with a target member 66 wherein the target member 66 is mounted on the cylindrical exterior surface of the drum 12 the sensors 62 and 64 are electrically linked via an electrical terminal junction strip 84 of a type known in the art to the circuit assembly 60 which is used to selectively energize electrically linked first and second led indicators 72 and 74 which project through the top surface of housing member 14 when the target members 66 activate the sensors 62 or 64 the corresponding led indicator 72 or 74 is illuminated the target members 66 may consist of metallic strips or any other construction for such device known to activate the associated position sensor 62 or 64 when an associated target member 66 is aligned with the sensor the target members 66 are fastened to the drum 12 by fasteners 70 through a slot 68 the fasteners 70 slidingly adjusts along the slot 68 formed within the drum 39 s external cylindrical surface 56 in the preferred embodiment the alignment of the target members on the drum may be adjusted approximately 15 u00b0 to accurately indicate the position of the drum in relation to the position of the rotatable valve apertures 76 extending through the top of the drum 12 allow the internal portion of the fastener 70 to.