I have a new 40 ft Macdon FD75 with double knife drive. At first start up for the day the sickle will not start, belts move, but sickle moves slightly and stalls. I reverse it several times(Lexion 740) and sickle reverses just fine. Sickle is free. Takes about 6-8 tries and then sickle finally takes off. I kind of hear oil flow sound and motors take off. After the 1st start, always restarts fine any time I reengage header. Oil level is fine. Is this the nature of them? Any ideas?