MotosportsJP's interview with Hasegawa San Vol 1.
Basically google translation,with some correction.

--Look back on this season and tell me what you have to keep in mind.

"First of all, we were unable to run satisfactorily in the first winter test and it was a big minus, which was technically not a big problem, but lack of preparation was revealed.Winter test is a very important test but it can only run for 8 days (4 days x 2), even if the schedule of disjointedness is good for 8 days, it will be done in 2 weeks at a stretch, so if we had some problem in the first day,it will effect the next days work.So i means there was no time to get back when we failed.The biggest thing was that we could not run properly, the program did not start well. "

---What was the problem with the winter test?

"The oil tank did not work well, We tested it on the bench with Gforce simulation,but it was worse than we expected when on the track.In short there is not enough preparation.It is the basic concept of the engine this year By changing the position of the compressor in the turbo, the oil tank was forced to change shape to avoid it, because of its shape, the oil was biased during deceleration and it did not absorb well. "

--How long did the problem last?

"As soon as we dealt with the problem, we came to be able to run soon.On the other hand, this is not a problem of ours, but the shakedown test scheduled one week ago is delayed because some problem from Mclaren side.When shakedown was working as planned, the measure should have been able to be done .... F1 was truly limited in running time, so the response to that was sweet. "

--Several problems came out since the season started.

"The next stuff is Bahrain, in the Bahrain there were four turbo destroyed in a stretch, Stoffel could not run, it was a big failure, but not only in Bahrain, but similar things happened in the whole first half of the season. It was not a big mechanical problem,but it happend again and again... ... For example, in Australia it was great that we had lost something like brakes or drive shafts.So many issues. "

--When did you settle the turbo problem in Bahrain?

"Unfortunately the turbo problem has been tailed to the end, as it took time to fix it after the problem was found, but since measures were taken, reliability and performance rised a bit I think. "

--What was the specific problem with the problem of the turbo?

"This year the shaft got longer due to changing the location of the turbo.There was a problem with the bearings supporting that shaft.It is MGU-H rather than the turbo itself, after all the bearing breaks. It is not a responsibility of the bearing maker but a problem of how to use it, because it was not supposed to use it, it is a matter of design.The problem of the turbo has indeed drawn the tail. "

--What kind of symptoms does the bearings of the shaft of the servo get burned?

"It will break the engine with a single shot."

--If it breaks, you have to change the engine. Then you can penalize it?

"We used four engines for both cars before the summerbreak, it was a terrible situation that I got a grid-down penalty every time I opend a new engine, which was a big penalty anyway.The race strategy is going wrong and the driver's motivation Because this penalty system is not good, it ruins the game, it is not the driver's responsibility. "

--In the past, you can use the engine without any limits.

"When I was doing in the third stage We could test all the time during the season and the engine for the race was putting in a one race at a time.We repeatedly tested it during the summerbreak and used the good engine to the next race. The engine was also broken, but the damaged one has ended in the race, and the next race we will have a new engine.It is different now.But it is regulation, So We had to make a corresponding movement, and I myself had to change my mind, we did not do well. "