A little info on your mom's organ, then. No problem. The J series dates from the mid 1960's, Hammond's attempt to make a low-cost transistor spinet organ, which they did by associating with another company that made a little organ called the Everett. This became the 'Everett by Hammond', then 'Hammond Everett'. It then became branded as the Hammond J100, with a few more keys (44 per manual as against 37) and slightly different shaped switches. The 200 added a Leslie unit and the 300 added coloured tabs in 1967, but otherwise they are the same as the J100 series. The series ended in the early 1970's, with the almost identical 400 and 500 series, which had a small rhythm box.
As for value, the home organ market is practically non-existent these days and prices are as low as they've ever been. A fully working J is perhaps worth $10-25. Ebay prices are often ridiculously high, with no bidders, so don't take any notice of them. A non-working J of any type is worth zero, sorry. Your mom's comes into that category as there's obviously something wrong. It doesn't need a tone cabinet of any kind as all the speakers are internal and it should be loud enough for home use. Sounds like it's got power supply or amplifier problems. It would cost more to fix than it's worth.
Keep it, and enjoy it as a musical instrument or piece of furniture.
Andy
It's not what you play, it's not how you play. It's the fact that you're playing that counts.