Hi phill,
I just had a chance to review your account, and the API error message you received is indicative that your description contains some objectionable Javascript code which is not allowed based on eBay policy.
The specific code which triggered this error in your last scheduled listing is located at the end of your description HTML, beginning with <!--eBayMobile-End--> and ending with <script src="safari-extension://com.ebay.safari.myebaymanager-QYHMMGCMJR/78e07d74/background/helpers/prefilterHelper.js" type="text/javascript"></script>
If you click the “Source” tab on the description editor within this listing to get to HTML mode and then delete this code, I believe you will then be able to post this listing successfully.
I have dealt with a few users in the past who found that this code was regularly added to their descriptions by the My eBay Manager extension for Safari so, if you are using that extension, it is possible that it caused this code to be added to your item automatically.
Provided that is the case, I suspect you should be able to avoid encountering this issue again by disabling the My eBay Manager extension within your Safari browser.
If you need any further assistance with this, please contact our Customer Support team directly from under the "Help" tab within your account.
-Mike