The market reaction to Aggreko's third-quarter trading update on Friday was far from positive, but analysts on the whole have retained their upbeat long-term stances on the stock with the majority recommending investors to 'buy on weakness'.The temporary power and temperature controls group had a more or less 'in-line' third quarter but extra bad debt provisions and adverse foreign exchange rates saw shares fall in morning trade. Meanwhile, full-year guidance was rather mixed with some parts of the business expected to perform better and worse than expectations.As such, Investec reduced its full-year pre-tax profit forecast for Aggreko from £376m to £365m, of which £8m is due to the bad debt provisions and £3m is currency related.Nevertheless, the broker maintained its 'buy' rating and 2,520p target price for the shares.Investec analyst John Lawson said: "The stock is likely to be weaker today, we believe, due to the likely adjustments to forecasts (and the high rating), but we remain convinced that the longer-term fundamentals of the investment case remain very sound (mostly, due to the structural growth drivers) and would see any sell-off as an opportunity to top-up holdings."Seymour Pierce also maintained its 'buy' recommendation and 2,500p target price.Though analyst Caroline de La Soujeole admits that consensus profit estimates are expected to come down - Seymour is now reviewing its own - the shares trade at 21.2 times prospective earnings "which we believe is not demanding for a business expected to deliver double digit earnings growth over the foreseeable future."Jefferies too retained its 'buy' rating and 2,800p target, but Panmure Gordon trimmed its target from 2,228p to 2,159p and reiterated a 'hold' recommendation, saying that the company is more cautious on 2013 than before.By 09:44, Aggreko's shares were down 6.78% at 2,146p.