Alman, please measure the voltages (i.e. V1, v2, v3, v4, v5) for reference.
You'll have a better picture upon completion of ADA's instructed modification.
V2 is clamped by D3 & D4 ( and V5 by D5 &D6 on the negative rail) . If V1 is much higher than V2 (and V4 >> V5), the voltage drop in R16 (and R18) will dissipate plenty of heat.
Lowering the V1 (and V4) will solve the overheat problem, comfortably.