Replaced filter which was considerably restrictive with new merv11 filter. The static pressure dropped dramatically after this. Replaced the high voltage power supply with new whip with a proper earth ground. Relocated the zone board off the top of the furnace and mounted it onto the support truss. Extended the low voltage wiring between the zone board and the furnace circuit board with new wires. Ensured extra wires were grounded to common. Replaced 40VA transformer powering zone board and air scrubber with a 75VA to tolerate the load. Tested system and equipment is operating properly at this time.