Airtemp 42124401421 gas furnace motor noise

[Bjorn]

Heating season just starting here in Minnesota and when the blower runs there is a new noise the furnace hasn't had in prior years - a mild moaning or groaning noise of a type which makes me think the motor is in the early stages of an eventual failure.  I get nervous at the thought of having an emergency service call three months from now when it is 10 below zero.  So, here are my questions:

First, is there anything I can investigate further or try myself in hopes of reducing the likelihood of a potential repair call this winter?

Second, if the motor does go or should be replaced now, is this something I could do myself?

Third, this furnace is more than 25 years old.  It has proved reliable through that time with minimal service costs, mostly cleaning.  Given the age and probable low  efficiency of the furnace, is it more cost-effective to replace it?  Money is tight right

now so that is a factor in balancing the limp along vs replace equation.  On the other hand, it is an old house and a cold climate and heating per month is high so there clearly could be a substantial payback to greater efficiency.

[hvacdrd]

Sounds like worn motor bearings. Grasping the motor shaft and moving it up and down (perpendicular to the motor) you should not feel any play. Side to side movement is normal. If all it takes is a new motor to keep it rolling you shouldn't be in for more than $100-$150 if you do it yourself.