On the I/O board I have seen that it has two tracks deliberately cut. It is normal? Should I fix them?
1) The board shown is a Lisa 2/5 I/O Board, not a 2/10 I/O Board.
It will work in a 2/10 regardless, but you should check that your motherboard matches the chassis harness as these are not interchangeable between the 2/5 and 2/10.
A 2/10 Motherboard does not have a back panel parallel port (it has only two DB-25s for serial ports). A 2/10 chassis harness has one 26 pin and one 20 pin ribbon cable in the drive cage.
A 2/5 Motherboard has a back panel parallel port (making three DB-25s, including the two for serial ports). A 2/5 chassis harness has two 26 pin ribbon cables in the drive cage, and if it has a 3.5" floppy drive, a "Lite Adapter" board connecting the drive to one of the cables.
2) The cut under C34 was done at the factory by Apple; it is normal, so you should not bridge the cut.
3) The cut under C33 is the style of an Apple modification, but Apple did not add large capacitors to the rear of any boards AFAIK, so there is something odd about that, can you provide a picture of the entire topside of the board?
4) There are likely to be wires 'tacked' on the component side; Apple made some modifications in that manner too.
5) Aside from repairs, some boards may exist that have non-Apple modifications -- if there are any, they are rare. An exception is that there are numerous 512K memory boards that have been user upgraded to be 2MB boards.
edit - added memory board exception
