Much has been written about 2068 problems and solutions. I have had an on-going problem with the Oliger equipment. At times the system would not initialize, or the disk drives would not run, or the system would just stop operating. Usually a jiggle of the circuit boards would temporarily get it going again. There are 4 circuit board slots that have 3 boards installed. Sometimes shifting boards around would seem to be the answer.
Recently desparation took hold and all board contacts were again cleaned with new cleaner. The 2068 port board was well cleaned. It worked for a time and then the same old problem. I then considered springing the mother board slot connections to make them more secure but the design of the contacts limited this action. However, the connector for the 2068 contacts 1s made differently and the springs will move slightly. A small diameter pin forced behind each phosphor bronze spring moved the spring inward slightly. After a full treatment on this socket, all is again well. The boards, mother board, and other parts can be wiggled and no drop out.
Perhaps there are readers out there who have had trouble with add-ons of various types. This solution may be helpful. I should note that the Oliger board uses a particular connector for connecting to the 2068 board because of the need for long solder pins. The 4 mother board connectors are of different design and are quite secure.