The fact that yours has been cut and joined means little, i doubt any supplier will agree with cutting the transducer cable? There is many factors that affect cable joins/splicers and the most elaborate splicing will still create problems, maybe immediately, maybe later or affect signal (IE the data). further more if the newer digital sounders are sending true digital signal down the cable there is other issues.
You are much more likely to have long term success re terminating a plug on the end or using an adapter, but once again for folks reading this, modifying your cable in any way will almost certainly void your warranty.