@Pheppy wrote:
In my case motor 1 was significant (25%) faster than motor 2. I've switched left and right, but the same result. My webshop was very helpful sending me a new motor 3. However the new motor 3 is even faster than motor 1, my guess is again 25%. Combining motor 2 and 3 results in a very small circle instead of a straight line. I tried that one to be sure I did not mix op motor 1 and 2. Conclusion, the extra motor did not help me very much. It looks like the mBot has some motor issues. I have the 2.4G Wireless Serial USB version. And I hope my webshop will solve my problem.