Very low volume with PS2

Yes Gary.  That can happen and replacing the speaker (16ohms) should do it.  G

Yes, the magnet will pickup everything as the engine travels.  also as time goes on the speaker cone can deteriorate. 

I have had this across the bench a few times,

first test the volume pot ans be sure it is not the cause, then you can check the speaker.  if you have debris collecting on the magnet, there is probably more inside, I would replace the speaker with a known good one.  that is probably the defective part.  But without having it in front of me to test I cannot be 100 % certain.

hope this helps

Thank you both for the fast replies.  I am going to put an ohm meter across the pot this morning.  However I don't know what the correct readings should be but I assume I should see a higher reading at a lower pot setting and a lower reading at a higher pot setting if it is working correctly.  There is  hobby shop that is an authorized MTH dealer near my house.  I will see if they have a replacement speaker.  Otherwise GGG I can let you know and if I need to get one from you.

Thank you both.

Pot center to one side is 10K and other 0 ohm, reverse when turned opposite direction.  I have not run into a bad pot for MTH.  G

I strongly suggest you do NOT power up any more before replacing that speaker.  They will sometimes short the coil to the frame and take out the audio amp, or worse.  The speaker is bad, so address that first!

Well hopefully I didn't do damage to the amp.  Volume is very low even with the volume pot turned all the way clockwise.

GT you are probably OK.  The 5V boards are different than the 3V and the 5V audio amp seems to be sturdier. The typical failure for your 16 ohm speaker is the flaking of the magnet coating falls off and collects internally and starts to hamper the vibration of the coil.  This reduces the sound output and distorts certain frequencies.

I have gone through a lot of 5V 16 ohm speakers with this issues and none have damaged the audio amp.

The 4 ohms speakers have occasionally had shorts.  I guess the larger current because of the lower resistance plus the smaller SMD audio amp means that it can be effected easier.  Or the speaker wire touches the frame and cause an AC short.  On the 4 ohms speakers I have seen where the whistle button causes the speaker to over drive and short, it usually just causes the board to shutdown an then restart. Certainly I would be careful with a speaker that shorting.  But the typical flaking magnetic coating has nothing to do with an internal short of the coil wire.   G

My local hobby shop does not have the speaker.  GGG, you said you have them?  Can I order one from you?