Antenna motor for Lexus SC300 continues to run after mast is retracted

[MichaelRM]

The antenna motor for my 1995 Lexus SC300 continues to run after mast is retracted.  Anyone else had this problem?  Should I buy an aftermarket replacement antenna assemble on eBay (the original part is discontinued).

[dcfish]

The mast is broken, Get the replacement.

[MichaelRM]

I don't think it is the mast, which goes up all the way when I turn on the radio and then retracts fully when the radio is turned off.  The motor keeps running for another 25 seconds or so once the mast is fully retracted.  Any further thoughts?  Should I just get an aftermarket entire unit with the motor?  I did replace the mast about 2 years ago and it worked fine until now.

[dcfish]

Maybe the last few teeth on the mast are worn down enough to let the motor run ?