It should recognize getting close to the end of tape and start reducing the
power / revs of the motor but it once continued at full revs to the end of
tape. Been monitored by human since it happened. It does not speed up if
human stops the motor close to end, goes normal speed to the normal clear
tape auto stop if REW is engaged again ofter pre-emptive stop.

I'm thinking a break in the line from the fast , take up spool sensor, so
less pulses coming from it and false interpretation.

I've seen that with these short length tapes that have big reels. The
VCR always thinks they are in the middle and FF and REW full speed the
entire tape.
Philips VCRs trigger their brake when the end sensor detects end of
tape, avoiding a possible tape break.