Elecrolytic Capacitor Replacement Dilemma

[stolz]

Hello - I am wanting to replace the 6 larger can electrolytic capacitors in the power supply section of my NAD 2100 stereo amplifier which is about 30 years old.  Two of these large electrolytic caps are the four pin snap in type consisting of a terminal for the positive, a terminal for the minus, and 2 terminals for mechanical support.  I found 2 possible replacements on Digi -Key and the spec sheets for both of these caps have the following cautions from the manufacturers:

     "Use dummy terminals for mechanical support only. Make no electrical connection because they resistively connect through the electrolyte to the negative terminal."

     "Use the blank terminals for mechanical support only. The blank terminals must not be connected to a solder trace on the PC board, but be electrically isolated from the negative or positive terminal."

However, my dilemma is that when I look at the underside of the circuit board I can clearly see that these support pins of both of these capacitors are soldered onto traces that lead back to the negative terminal of the capacitors, and clearly this is in complete contradiction to what the manufacturers are saying.   Can I safely install these 4 pin capacitors in the SAME WAY as the original ones are soldered in?

Could it be that the designers of the NAD  amplifier overlooked what the capacitor manufacturers are warning against, or possibly that the way the capacitors were made 30 years ago allowed for the support pins to be soldered to traces that went to the negative pin?  Or, could it be that the capacitor manufacturers are just "over warning" against a potential degradation that can happen over time and/or just covering their butts to prevent lawsuits?

The amplifier currently is working well and sounds good to me.  I am reading in many places that old electrolytic capacitors should be replaced. I am wanting to replace these power supply capacitors to prolong the lifetime of this amplifier and to prevent potential damage that could occur if these capacitors might blow up or get shorted.  These capacitors seem to be very slightly rounded (convex) at the top but there are no signs of leakage.

Also, would it be reasonable to just replace these 6 large power supply capacitors and leave the other 30 very small electrolytic caps alone, or should I definitely replace ALL of the electrolytics which would be very tedious?

Any suggestions or input would be very much appreciated and thank you for your time.

[wraper]

"Use dummy terminals for mechanical support only. Make no electrical connection because they resistively connect through the electrolyte to the negative terminal."

According to fist warning you can safely connect them to negative terminal.