I have had the “IBTS connector not quite firmly seated, thus preheat limited to 205°C” problem in the past, and this seems somewhat related. Here’s what I saw just today, which now makes a second time:
When I turned on the Bullet, it took a long time with fans whirring but the display was black, and it beeped a lot, then finally the display came alive and said “the bullet is now ready”, but the IBTS fan wasn’t running, and the preheat was limited to 205. Since the machine had worked a few days earlier and has no jostling between roasts, I decided to power cycle, but got the same behavior (and no error logs in RoasTime). So I took off the front plate (power was still applied) and was fiddling with loosening the PCB screw on the lower left when I heard the IBTS fan start going. So I reassembled the front panel, and power cycled again. It let me set my preheat to 300°C, so I set my timer for 18 minutes, which is how long it normally takes to get to 300.
Here’s the weird part: after 15 minutes, I checked in on it, and RoasTime said the machine had been at 300 for about 5 minutes already, plus, the IBTS probe and Bean Temp probe were wildly divergent (more than I’m used to). I have tried to roast in this mode, and it’s clear that the preheat is nowhere near 300, and everything goes awry from there. So instead of proceeding to roast, I unplugged the bullet and immediately plugged it back in. The IBTs registered 200°C, which was much closer to what I believed to be the truth. I resumed my preheat to 300, and had a terrific roast.
Here is a screen shot of RoasTime during the bad - then continued good preheat.
The subsequent roast was https://roast.world/my/roasts/DPIGEsh1VzY2AglISr0fb
Anyway, I thought I’d post this here - if your preheats seem to take 5 or so minutes less time than normal, it’s worth a reboot to verify. Other than that, I’ve been having great roasts with 300°C preheat / P7 for 750g, or 310°C preheat / P8 for 1kg.