Did a Google image search for these locos and found that they actually make replacement/spare chassis for them. MB Klein's (modeltrainstuff.com) carry them when they're available. This is the power chassis, presumably the DC version which I also assume is what you've got.
https://www.modeltrainstuff.com/Bowser-HO-4299-Baldwin-AS-16-Power-Chassis-p/bow-4299.htm .
They also make replacement DCC/sound replacement chassis, now with ESU Loksound decoders
http://www.modeltrainstuff.com/Bowser-HO-Baldwin-AS-616-Powered-Chassis-p/bow-1221.htm
Although this one, also from MBK's listings says Loksound, it looks to me that it is the now superseded Tsunami one, a photo misprint I would say
https://www.modeltrainstuff.com/Bowser-HO-Baldwin-AS-16-Powered-Chassis-p/bow-1220.htm
What do you reckon on those Terry, that Tsunami with it's big caps certainly looks like the early version.