Easily 18" per second. If they use the 2 CIM motors (I don't know what Tyco motors are) with a gear ratio of around 61:1 and a 6 inch spool, at 40 amps they could lift around 234 lbs (depending on efficiency ... I used .95^4) and go 18" per second. What this means is that they really are moving almost 2x that speed if another robot isn't hanging on them.
Sounds to me like someone is taking power from their drive wheels .......