I have just bought a second hand Gene roaster and have tried it out for the first time, so I'm not sure exactly what to expect. I set the temperature for 250 degrees C and 19 minutes. (The user manual's recommendation for a full city roast) I watched the actual temperature during the whole heating cycle, and it only got to 230 degrees by 19 minutes; so it never reached the 250 degree set point. Is this normal, or if it's a problem, has any one else come across this behaviour.

The Gene does ramp up over a period of time to the set temperature, although I tend to see around the 230 mark after 12 minutes (around 1st crack). 19 minutes to reach 230 seems too long to me (I assume you meant 230 and not 23, or are you roasting at the south pole? ).

EDIT: What I do is: 5 minutes at 150 (drying), then 12 minutes at 250 (to 1st crack), then down to 230 when 1st gets started until I stop the roast.

I believe the heating element degrades over time, so it may be you need to replace it.

It possibly just needs cleaning out. The behaviour of the sensor depends a lot on the airflow through the roaster. There are a couple of things that could upset that airflow. If you look underneath the roaster, you'll see some mesh. Make sure that that is brushed or vacuumed (preferably vacuumed) clean. Also, one thing that is often forgotten is to periodically clean out the chaff collector. To do that, remove the six screws at the bottom of it, pull the two halves apart, and then undo a few more screws and remove the grill of the chaff collector itself. This latter often has a considerable accumulation of chaff on it. It's very important to clear this off. Be careful with the screws, some of them are of slightly different length.

Another possibility is the amount of beans in the roaster. If the beans produce a lot of chaff, it may accumulate on the air outlet and partially block it; as the sensor is on the other side of that outlet, the reading may be incorrect for a while. I've had best results using 230 g every time.

Anyway, as it's a secondhand unit, these points are well worth checking.

I took Hazbean's advice and opened up the machine to clean it out. I discovered that the screws coupling the duct that leads from the heating unit to the bean hopper was loose. I tightened up the screws and now the temperature does get up to 250 degrees before the end of the roasting cycle.

My second roast was much more successful; more of a full city with good body.

I have been using this roaster for about four years. I find it's more likely to reach it's set point if you roast a smaller batch of beans....