Here is a list of the components needed in case anyone else wants to do this upgrade. Mouser project link
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?State=EDIT&ProjectGUID=47A658EE-03E5-4F0B-B692-6F3F37C9A2D7
And components in case that doesn't work:
HeaterMeter 4.0 to 4.2
Mouser # Mfr. # Manufacturer Desc. RoHS Lifecycle Customer Part # Order Qty. Price (USD) Ext.: (USD)
291-100K-RC 291-100K-RC Xicon Carbon Film Resistors - Through Hole 100Kohms 0.05 RoHS Compliant 5 $0.10 $0.50
291-68K-RC 291-68K-RC Xicon Carbon Film Resistors - Through Hole 68Kohms 0.05 RoHS Compliant 1 $0.10 $0.10
291-22K-RC 291-22K-RC Xicon Carbon Film Resistors - Through Hole 22Kohms 0.05 RoHS Compliant 1 $0.10 $0.10
291-2.2K-RC 291-2.2K-RC Xicon Carbon Film Resistors - Through Hole 2.2Kohms 0.05 RoHS Compliant 2 $0.10 $0.20
594-K104K15X7RF53L2 K104K15X7RF53L2 Vishay Multilayer Ceramic Capacitors MLCC - Leaded 0.1uF 50volts 10% X7R 2.5mm LS RoHS Compliant By Exemption 4 $0.10 $0.40
511-1N5819 1N5819 STMicroelectronics Schottky Diodes & Rectifiers Vr/40V Io/1A BULK RoHS Compliant 1 $0.41 $0.41
512-BS170 BS170 Fairchild Semiconductor MOSFET N-Channel MOSFET RoHS Compliant 1 $0.39 $0.39
512-FQU11P06TU FQU11P06TU Fairchild Semiconductor MOSFET 60V P-Channel QFET RoHS Compliant By Exemption 1 $0.87 $0.87
652-RLB9012-221KL RLB9012-221KL Bourns Fixed Inductors 220uH 10% 1A RoHS Compliant 1 $0.58 $0.58
647-UPW1E470MDD UPW1E470MDD Nichicon Aluminum Electrolytic Capacitors - Leaded 25volts 47uF 5x11 20% 2LS RoHS Compliant 1 $0.16 $0.16
523-RJHSE-5080 RJHSE-5080 Amphenol Modular Connectors / Ethernet Connectors R/A RJ45 NONSHIELDED 8 CONT NO LEDS RoHS Compliant 1 $0.91 $0.91