I attended demand call for Tracy in the Cochrane area, during my inspection I found the furnace to be tripping on high-limit due to a clogged filter. The blower motor / inducer motor also contain dust in the windings which is damaging the components. Inducer motor exceeding rated capacity set from manufacture. The gas valve failed on 3 different attempts of ignition, flame sensor readings fluctuating beyond normal operation. Partial flame roll out occurring and beginning to scorch HSI wires. Currently the system is running intermittently. I have provided Tracy with options for repairs vs replacement and she has chosen to go ahead and purchase a new furnace. Currently the install is booked for Tuesday Feb 7. Tracy is renovating the basement and would like to wait until spring to have the ducts cleaned.