Hi, Purchased a TT120 A4 (William Whitelaw in a non HM7000 set). Purchased a HM7000 Next18 chip, and fitted. However, sound comes on but when it starts to go, it cuts out (like its a short or something as connection also gets lost to app). Worked fine on dc before and when I restore loco back with a blanking chip. Any ideas or issues encountered with this chip / loco combo please thst might help me? Cheers