Exemption scope narrowed: amendment omits phrase 'in the repair or maintenance of machinery used', altering notification coverage. The Central Government, under Section 5A(1) of the Central Excises and Salt Act, 1944, by Notification No. 234/88-C.E. dated 27-7-1988, amends Notification No. 182/87-C.E. (10-7-1987) by omitting the words 'in the repair or maintenance of machinery used' from that notification.