Mine exhibited the same symptoms. As youve noted, it would fix itself quickly.
Then, one day, it stalled completely, and before my brain caught up *:-[ (maybe a couple of seconds) it started to fry. I got to the power switch more or less in time but it wouldnt start afterwards.
I let it cool down and then completely disassembled it. There was no obvious damage, but there was a fair bit of chaff and assorted debris inside so I gave it a good clean and manually turned the motor over a few times.
After re-assembly, it appeared to work again but the temperature readout was wildly inaccurate (reading high) and it ruined a batch of beans.
I added a new program with really high temps and managed to get it to struggle past first crack. I persisted for another 3-4 roasts (over a week or so) and then it seemed to start working more or less normally for a few weeks until, one day, it just blew cold air.
So, unfortunately, I dont have any good news and mine is just sitting in the cupboard gathering dust. I remember that hitting the "Cool" button when it hesitated seemed to "kick-start" the motor and I used to let it run for 5-10 seconds and then restart the roast.
My only other suggestion would be to keep one hand on the power switch when you hit "Roast" and power it down if it doesnt spring to life in about a second. Fast reflexes would be a help. Perhaps if you can avoid overheating it as I did, you might be able to nurse it for a while longer.