A few days ago it began to make a loud clunking noise as it ran

No loud noise too

At 3.5 mph makes loud motor noise- very nerve racking.

Furthermore, it made a horrible squeaking noise after 5 minutes of use

Purchased this treadmill in April of 2011, worked great for 5 months, then the belt started making strange noises

It started to make a weird noise and smell

love this little thing, takes very small room, but it started making loud noise after 15 months, cleaned once, not helpful, called gym tech, repair cost between $100 to $200

Does make nasty noises when not lubed properly

Very good I like it