If he had a problem with the balancer, just replaced the grenaded case doesn't fix it. Older (80s) VN750s can have the grommet dry out around the balamcer when this happens, the balancer wobbles, chews up the inside and eventually grenades the case.
The shifter not returning could be a popped circlip on the shifter shaft. Good way to tell is if there is a lot of in and out play on the shifter (Usually happens if it took a drop on the left side (also same side as a grenaded case)
Tach mount broken.. happens if it is allowed to vibrate too much. A wobbily tach will eventually crack the mount.
Balancer fix requires an engine pull, a loose shifter shaft can be mended with a collar to keep the shaft out.
You didn't mention what year it was but I am suspecting it's a pre 90.
Patriot Guard Rider
2000 VN750 Sere (Serendipity)
1990 GL1500 (Ole Blue)
1986 VN750 EVie (project bike, heavy custom)
VROC # 11628 / 25000-H
ARVROC # 12 Coordinator and Crowd Control
OKVROC # 18 (H)
TNVROC # 45 (H)