Thanks. I actually debated just fixing the heaters I have like you mentioned. Using silicon, or liquid rubber, etc. I decided against it due to the fact that if the heater was hot enough to melt the sealant that is currently in place it may have been a few degrees away from melting the cable insulation. This could lead to the insulation becoming brittle and breaking or having a shorter life. It's an area (electricity submerged in water) that I don't feel I need to save a few dollars now and regret it later. 6 months from now, or 6 days, I won't think about the old heaters ever again. Move on the right way and for me the right way is to replace them.This does not make the decision for you, but may help with your considerations.
I am debating a pair of 200w replacements now.