I haven't seen or heard of this problem before. You might be able to weld the original contol-arm mount back together. You may need to fabricate and add reinforcements to the repair. It all depends on how good a welder/fabricator you are and if you believe you can make a reliable repair with the crossmember (also kown as a 'subframe') installed in the car. If you have any doubts, you would be better off replacing it. Wether you decide to repair or replace the subframe, it's possible to fabricate an engine support bar and chains to straddle the inner wheel housings or front fenders (fenders heavily padded with thick telephone books of course) and remove the subframe while the engine remains in the car. If you wind up removing the subframe, that would be a good time to replace any bad mounts. Good Luck.

Happy Motoring, Mark

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DrDKW