Noises: There are various noises from the motor and drum that also change as it heats up. Sometimes tightening the front brass screw will stop them as it pulls the drum away from where it can touch
Chaff: One of the Hottop's weaker points. I empty tray. Put it 1/2 way back in then unscrew front and let the rest drop into the tray. Close tray and blow into chamber then empty tray & them vacuum between every roast.
Alerts: there are 2 alerts; A1 - If it reaches 180deg within the 1st 8:30 mins it will alarm. If not you will not get the 1st alarm. A2 - when it reaches 210deg. This is a safety in case you arnt being attentive, in which case it will shut down/eject etc.
>250g: I have never been able to roast more than 250g without it giving me grief of some type. I have tried to roast enough so you can still get 250g after the %loss but to no avail, and a few binned roasts. Most recently in August this year I tried 305g. The result was it failed to eject/unload, and as I have the older version, there is no manual eject. Probably still worth giving it a try though.
Filter: You will also find the fans effectiveness is affected to some degree as the filter deteriorates.