Retention of duty-paid goods permitted in factory subject to Collector's conditions, documentation, time limits and non-manufacture removal. The substituted rule 173H prohibits retention or bringing into a factory or warehouse of duty-paid excisable goods except under specified exceptions: use in manufacture; for construction, repairs or fittings; for re-making, refining or repair; when transport is prevented by circumstances beyond control; or for testing or study. Such goods should be accompanied by duty-paying documents unless identity is shown by collateral evidence and the Collector permits relaxation. Goods returned for repair/reconditioning must be brought back within one year of removal or within the warranty period, subject to Collector's extension. Non-manufactured goods admitted under these permissions may be removed without duty under Collector-specified conditions.