[Hallicrafters] SX-42 Upgrades

[Chuck McGregor]

A listing on ebay that closed yesterday, offered a SX-42 "Upgrade kit" consisting of 3 tubes. It promised "increased sensitivity".  Can anyone offer any insights into this upgrade  or other SX-42 upgrades ?   I'm in the middle of a recapping ( and some re-resistoring) job and would like to know if there are any other smart things to do while I'm deep inside with the side panels off for access.

Thanks,
Chuck N7RHU