Distilled water (50C) 750 ml
Hydroxyethyl-o-aminophenol sulfate 6.0 g
Catechol 10.0 g
Hydroquinone 4.0 g
Sodium sulfite (anhy) 100 g
Sodium carbonate (anhy) 25.0 g
Potassium bromide 1.0 g
Sodium metaphosphate 1.0 g
Distilled water to make 1.0 l

Since HEAP is no longer available I would suggest subtituting Metol which is chemically similar. Since the molecular weight of these two developing agents and their activity are different some adjustment in the amount would have to be made.