I assume the gen 1’s do not have a “plug” for the speaker cable? I am not sure how those are set up.

I have also set up the same thing on AtGames ALU and pinball as well as the iircade and mvsx cabinets. Those do not have the 3.5mm speaker plug, so to get around that, I integrated this line out converter straight into the speaker wires. From there there is just a RCA cable connecting the subwoofer to the converter. Works loke a charm.

Kicker KISLOC 2-Channel K-Series Speaker Cable to RCA Adapter with Line Out Converter https://www.amazon.com/dp/B00I4EF1BC/ref=cm_sw_r_cp_api_glt_fabc_E6YM6KNJMV5SWDEXS2RK?_encoding=UTF8&psc=1