My Honeywell Truesteam HM512 humidifier threw an error code this week. The troubleshooting manual states "The backup weld monitor input is active when the backup heater relay is off." There are two Tyco T9AS5D12-22 relays controlling the heating coil. My guess is that one of them welded shut. I'd like to take a stab at replacing them for $9 before tossing the unit and spending a $1000 on replacement. Clearing the service code allows the unit to run for a few hours before tripping again, so I can possibly perform some tests with a meter to verify my assumption.
My question is, can someone recommend a good set of tools to complete this repair? Iron, solder type and size, etc. I already have some 0.10" Chemtronics wick to remove the old component. It's been 15 years since I last soldered and my old tools were lost in a move. Things have obviously changed a lot since then and some fresh recommendations would be helpful. The vast selection on the web is overwhelming.
FYI, I've done significant work with 120/240 residential wiring, so I understand the dangers and know how to work safely.
Appreciate your help.