i have a nordyne m3rl060a bw s/n m3a 070103998 propane furnace. My problem is that the inducer orifice restrictor appears to have disintegrated again after replacing it last year. The vent switch keeps tripping out & needs to be reset again. Has there been an upgrade in the material of construction on replacement orifices? What is the correct part number to order? Please call me @ 716-807-4422.